diff --git a/backend/app/services/website_client.py b/backend/app/services/website_client.py
index 8c348f0..f9fac59 100644
--- a/backend/app/services/website_client.py
+++ b/backend/app/services/website_client.py
@@ -3,7 +3,7 @@ from __future__ import annotations
 import logging
 import sys
 import time
-from decimal import Decimal, InvalidOperation, ROUND_HALF_UP
+from decimal import Decimal, InvalidOperation, ROUND_HALF_UP, ROUND_UP
 from typing import Any
 from urllib.parse import quote, urlparse
 
@@ -66,25 +66,16 @@ def calculate_target_rate(values: list[Any], percent: Any = 0, algorithm: str =
     elif algorithm == "max_plus_percent":
         base = max(rates)
     elif algorithm == "priority_weighted_plus_percent":
-        rates_sorted = sorted(rates)
-        N = len(rates_sorted)
-        if N == 1:
-            base = rates_sorted[0]
-        else:
-            w1 = Decimal("0.85")
-            w_others = Decimal("0.15") / Decimal(N - 1)
-            base = rates_sorted[0] * w1 + sum(rates_sorted[1:], Decimal("0")) * w_others
+        min_rate = min(rates)
+        max_rate = max(rates)
+        raw_target = max(min_rate * Decimal("1.50"), max_rate * Decimal("1.10"))
+        return raw_target.quantize(Decimal("0.01"), rounding=ROUND_UP)
     else:
         raise WebsiteError(f"不支持的算法：{algorithm}")
     pct = Decimal(str(percent or 0))
     if pct < 0:
         raise WebsiteError("百分比不能为负数")
-    target_rate = (base * (Decimal("1") + pct / Decimal("100"))).quantize(Decimal("0.01"), rounding=ROUND_HALF_UP)
-    if algorithm == "priority_weighted_plus_percent":
-        min_rate_2d = min(rates).quantize(Decimal("0.01"), rounding=ROUND_HALF_UP)
-        if target_rate < min_rate_2d:
-            target_rate = min_rate_2d
-    return target_rate
+    return (base * (Decimal("1") + pct / Decimal("100"))).quantize(Decimal("0.01"), rounding=ROUND_HALF_UP)
 
 
 def _unwrap_data(value: Any) -> Any:
diff --git a/backend/app/services/website_sync.py b/backend/app/services/website_sync.py
index f7cf48a..ae68a0d 100644
--- a/backend/app/services/website_sync.py
+++ b/backend/app/services/website_sync.py
@@ -2,7 +2,7 @@ from __future__ import annotations
 
 import json
 import logging
-from decimal import Decimal
+from decimal import Decimal, ROUND_HALF_UP
 from datetime import datetime, timezone
 from typing import Any
 
@@ -14,7 +14,7 @@ from app.models.upstream import Upstream
 from app.models.upstream_key import UpstreamGeneratedKey
 from app.models.website import Website, WebsiteGroupBinding, WebsiteSyncLog
 from app.services.auth_config import normalize_auth_config
-from app.services.website_client import Sub2ApiWebsiteClient, WebsiteError, _extract_id, calculate_target_rate
+from app.services.website_client import Sub2ApiWebsiteClient, WebsiteError, _extract_id, calculate_target_rate, parse_positive_decimal
 from app.services.upstream_client import UpstreamClient
 from app.services import webhook_service
 from app.utils.number import fixed_decimal_string
@@ -168,6 +168,21 @@ def sync_binding(db: Session, binding: WebsiteGroupBinding, write: bool = True)
         })
     try:
         target_rate = calculate_target_rate([item.get("rate") for item in source_rates], binding.percent, binding.algorithm)
+        if binding.algorithm == "priority_weighted_plus_percent":
+            rates = [rate for rate in (parse_positive_decimal(item.get("rate")) for item in source_rates) if rate is not None]
+            if rates:
+                rates_sorted = sorted(rates)
+                N = len(rates_sorted)
+                if N == 1:
+                    base = rates_sorted[0]
+                else:
+                    w1 = Decimal("0.85")
+                    w_others = Decimal("0.15") / Decimal(N - 1)
+                    base = rates_sorted[0] * w1 + sum(rates_sorted[1:], Decimal("0")) * w_others
+
+                if base > 0:
+                    effective_percent = (target_rate / base - Decimal("1")) * Decimal("100")
+                    binding.percent = fixed_decimal_string(effective_percent.quantize(Decimal("0.01"), rounding=ROUND_HALF_UP), 2)
     except Exception as exc:
         return _log(db, binding, website, source_rates, "failed", str(exc))
 
diff --git a/backend/test_group_binding_create_sync.py b/backend/test_group_binding_create_sync.py
index 5378f14..d18d14d 100644
--- a/backend/test_group_binding_create_sync.py
+++ b/backend/test_group_binding_create_sync.py
@@ -387,3 +387,49 @@ def test_create_binding_does_not_notify_when_website_rate_unchanged(monkeypatch,
 
     assert result.target_group_id == "target"
     assert db_session.query(NotificationLog).count() == 0
+
+
+def test_sync_binding_auto_percent_writeback(monkeypatch, db_session):
+    website, upstream = seed_rows(db_session)
+    binding = WebsiteGroupBinding(
+        website_id=website.id,
+        target_group_id="target",
+        target_group_name="Target group",
+        source_groups_json=json.dumps([{
+            "upstream_id": upstream.id,
+            "upstream_name": "Upstream",
+            "group_id": "source",
+            "group_name": "Source",
+        }], ensure_ascii=False),
+        percent="0.00",
+        algorithm="priority_weighted_plus_percent",
+        enabled=True,
+    )
+    db_session.add(binding)
+    db_session.commit()
+    db_session.refresh(binding)
+
+    class FakeClient:
+        def __init__(self, **kwargs):
+            pass
+        def __enter__(self):
+            return self
+        def __exit__(self, *args):
+            pass
+        def get_groups(self, endpoint):
+            return [{"id": "target", "name": "Target group", "rate_multiplier": "2.0"}]
+        def update_group_rate(self, endpoint, group_id, rate):
+            pass
+
+    monkeypatch.setattr(websites_router, "Sub2ApiWebsiteClient", FakeClient)
+    monkeypatch.setattr("app.services.website_sync.Sub2ApiWebsiteClient", FakeClient)
+
+    from app.services.website_sync import sync_binding
+    sync_binding(db_session, binding, write=True)
+
+    db_session.refresh(binding)
+    assert binding.percent == "50.00"
+
+    log = db_session.query(WebsiteSyncLog).filter(WebsiteSyncLog.binding_id == binding.id).one()
+    assert log.percent == "50.00"
+    assert log.new_rate == "3.00"
diff --git a/backend/test_website_client.py b/backend/test_website_client.py
index 4e27aae..561893a 100644
--- a/backend/test_website_client.py
+++ b/backend/test_website_client.py
@@ -402,21 +402,18 @@ def test_list_accounts_pagination_returns_none_when_any_page_fails():
 
 
 def test_calculate_target_rate_priority_weighted():
-    # 0.18、0.25 + 50% 应得到约 0.29
-    assert calculate_target_rate(["0.18", "0.25"], 50, "priority_weighted_plus_percent") == Decimal("0.29")
-    # 单来源时等同于该来源倍率 + 百分比
-    assert calculate_target_rate(["0.18"], 50, "priority_weighted_plus_percent") == Decimal("0.27")
-    # 多来源时最低倍率占 85%，其余平分 15%：
-    # 0.18 * 0.85 + (0.25 + 0.38) * 0.075 = 0.20025 -> 0.20025 * 1.5 = 0.300375 -> 0.30
-    assert calculate_target_rate(["0.18", "0.25", "0.38"], 50, "priority_weighted_plus_percent") == Decimal("0.30")
+    # 0.18、0.25 应当至少满足 min * 1.50 (0.27) 和 max * 1.10 (0.275)，向上取整为 0.28，忽略 percent 输入
+    assert calculate_target_rate(["0.18", "0.25"], 50, "priority_weighted_plus_percent") == Decimal("0.28")
+    assert calculate_target_rate(["0.18", "0.25"], 0, "priority_weighted_plus_percent") == Decimal("0.28")
 
-    # 4 个来源以锁定均分 15% 的权重语义：
-    # 0.18 * 0.85 + (0.24 + 0.30 + 0.36) * 0.05 = 0.198 -> 0.198 * 1.5 = 0.297 -> 0.30
-    assert calculate_target_rate(["0.18", "0.24", "0.30", "0.36"], 50, "priority_weighted_plus_percent") == Decimal("0.30")
-    assert calculate_target_rate(["0.18", "0.24", "0.30", "0.36"], 0, "priority_weighted_plus_percent") == Decimal("0.20")
+    # 单来源 0.05 自动得到 0.08 (max(0.05 * 1.50, 0.05 * 1.10) = 0.075 -> ROUND_UP -> 0.08)
+    assert calculate_target_rate(["0.05"], 0, "priority_weighted_plus_percent") == Decimal("0.08")
 
-    # 验证保护线与精度保护：最低来源 0.124，应当四舍五入并返回两位小数
-    assert calculate_target_rate(["0.124"], 0, "priority_weighted_plus_percent") == Decimal("0.12")
+    # 4 个来源：min=0.18, max=0.36. max(0.27, 0.396) = 0.396 -> ROUND_UP -> 0.40
+    assert calculate_target_rate(["0.18", "0.24", "0.30", "0.36"], 50, "priority_weighted_plus_percent") == Decimal("0.40")
+
+    # 验证保护线与精度保护：最低来源 0.124。max(0.186, 0.1364) = 0.186 -> ROUND_UP -> 0.19
+    assert calculate_target_rate(["0.124"], 0, "priority_weighted_plus_percent") == Decimal("0.19")
 
     # 无可用正数倍率时报错
     with pytest.raises(WebsiteError, match="没有可用的正数上游倍率"):
diff --git a/frontend/src/views/Websites.vue b/frontend/src/views/Websites.vue
index 3c8ad58..03a4f67 100644
--- a/frontend/src/views/Websites.vue
+++ b/frontend/src/views/Websites.vue
@@ -158,7 +158,7 @@
             <div class="binding-main">
               <div class="binding-title">{{ binding.website_name }} / {{ binding.target_group_name || binding.target_group_id }}</div>
               <div class="binding-meta">
-                {{ algorithmLabel(binding.algorithm) }} + {{ binding.percent }}% ·
+                {{ binding.algorithm === 'priority_weighted_plus_percent' ? `${algorithmLabel(binding.algorithm)} · 自动约 ${binding.percent}%` : `${algorithmLabel(binding.algorithm)} + ${binding.percent}%` }} ·
                 {{ binding.source_groups.length }} 个上游分组
               </div>
             </div>
@@ -297,8 +297,8 @@
           </el-col>
           <el-col :span="12">
             <el-form-item label="百分比">
-              <div class="custom-percent-stepper">
-                <button type="button" @click="adjustPercent(-5)" class="stepper-btn">
+              <div class="custom-percent-stepper" :class="{ disabled: bindingForm.algorithm === 'priority_weighted_plus_percent' }">
+                <button type="button" @click="adjustPercent(-5)" class="stepper-btn" :disabled="bindingForm.algorithm === 'priority_weighted_plus_percent'">
                   <el-icon><Minus /></el-icon>
                 </button>
                 <input
@@ -308,8 +308,10 @@
                   max="100"
                   v-model.number="bindingForm.percent"
                   class="stepper-input"
+                  :disabled="bindingForm.algorithm === 'priority_weighted_plus_percent'"
+                  :placeholder="bindingForm.algorithm === 'priority_weighted_plus_percent' ? '自动计算' : ''"
                 />
-                <button type="button" @click="adjustPercent(5)" class="stepper-btn">
+                <button type="button" @click="adjustPercent(5)" class="stepper-btn" :disabled="bindingForm.algorithm === 'priority_weighted_plus_percent'">
                   <el-icon><Plus /></el-icon>
                 </button>
               </div>
@@ -2588,6 +2590,27 @@ onMounted(loadAll)
   margin: 0;
 }
 
+.custom-percent-stepper.disabled {
+  opacity: 0.6;
+  background: #0f0706;
+  border-color: #2b1c18;
+}
+
+.custom-percent-stepper.disabled .stepper-btn {
+  cursor: not-allowed;
+  color: #5c4a45;
+}
+
+.custom-percent-stepper.disabled .stepper-btn:hover {
+  background: transparent;
+  color: #5c4a45;
+}
+
+.custom-percent-stepper.disabled .stepper-input {
+  cursor: not-allowed;
+  color: #8c746b;
+}
+
 /* Custom Switch Toggle */
 .switch-toggle-line {
   display: flex;