diff --git a/backend/app/api/budget.py b/backend/app/api/budget.py
index fa6c2c6b..0c1bd227 100644
--- a/backend/app/api/budget.py
+++ b/backend/app/api/budget.py
@@ -10,7 +10,7 @@ from datetime import datetime
 from app.database import get_db
 from app.deps import get_entity_id
 from app.auth_middleware import require_auth, require_role
-from app.models import BudgetPlan, KPIDefinition, OperationLog
+from app.models import BudgetPlan, KPIDefinition, OperationLog, KPIValue
 
 router = APIRouter(prefix="/api/cma/budget", tags=["预算管理"],
     dependencies=[Depends(require_role("ceo", "finance", "it"))],
@@ -171,15 +171,106 @@ def auto_decompose_budget(
     db: Session = Depends(get_db),
     current_user=Depends(require_auth),
 ):
-    """自动分解年度预算到月度（均分或按历史权重）"""
+    """自动分解年度预算到月度（均分或按历史权重）
+    支持两种模式：
+    1. 单KPI：传 kpi_id + annual_budget
+    2. 批量：不传 kpi_id，分解该年所有已有年度预算的KPI
+    """
     kpi_id = data.get("kpi_id")
     year = data.get("year", datetime.now().year)
     annual_budget = data.get("annual_budget")
     method = data.get("method", "equal")  # equal / weighted
     version = data.get("version", "v1.0")
 
-    if not kpi_id or annual_budget is None:
-        raise HTTPException(400, "缺少必要参数: kpi_id, annual_budget")
+    # ── 批量模式：不传kpi_id → 分解该年所有有年度预算的KPI ──
+    if not kpi_id:
+        # 找该年已存在的年度预算（period=YYYY-00 或已按月填的KPI汇总）
+        # 优先用 budget_plans 中该年的预算作为年度总额
+        year_budget_rows = db.query(BudgetPlan).filter(
+            BudgetPlan.entity_id == 1,
+            BudgetPlan.budget_year == year,
+            BudgetPlan.status == "active",
+        ).all()
+
+        # 按KPI聚合年度预算总额
+        kpi_annual = {}
+        for r in year_budget_rows:
+            kpi_annual[r.kpi_id] = kpi_annual.get(r.kpi_id, 0) + (r.budget_value or 0)
+
+        if not kpi_annual:
+            raise HTTPException(400, "该年度没有可分解的预算，请先在预算执行中录入年度预算")
+
+        results = []
+        created_count = 0
+        for kid, annual in kpi_annual.items():
+            kpi = db.query(KPIDefinition).filter(KPIDefinition.id == kid).first()
+            if not kpi:
+                continue
+
+            # 计算各月权重
+            if method == "weighted":
+                last_year = year - 1
+                values = db.query(KPIValue).filter(
+                    KPIValue.kpi_id == kid,
+                    KPIValue.period.like(f"{last_year}-%"),
+                    KPIValue.actual_value.isnot(None),
+                ).order_by(KPIValue.period.asc()).all()
+                total = sum(v.actual_value for v in values)
+                weights = {v.period: v.actual_value / total for v in values} if total > 0 else {}
+            else:
+                weights = {}
+
+            monthly = []
+            for m in range(1, 13):
+                period = f"{year}-{m:02d}"
+                weight = weights.get(period, 1 / 12) if method == "weighted" and weights else 1 / 12
+                monthly_value = round(annual * weight, 2)
+
+                existing = db.query(BudgetPlan).filter(
+                    BudgetPlan.kpi_id == kid,
+                    BudgetPlan.period == period,
+                    BudgetPlan.version == version,
+                    BudgetPlan.status == "active",
+                ).first()
+
+                if existing:
+                    existing.budget_value = monthly_value
+                    existing.updated_at = datetime.now()
+                else:
+                    db.add(BudgetPlan(
+                        entity_id=1,
+                        kpi_id=kid,
+                        period=period,
+                        budget_value=monthly_value,
+                        budget_year=year,
+                        budget_month=m,
+                        version=version,
+                        status="active",
+                    ))
+                    created_count += 1
+                monthly.append(monthly_value)
+
+            results.append({
+                "kpi_id": kid,
+                "kpi_code": kpi.kpi_code,
+                "kpi_name": kpi.kpi_name,
+                "annual_budget": round(annual, 2),
+                "method": "equal" if not weights else "weighted",
+                "monthly": monthly,
+                "monthly_count": 12,
+            })
+
+        db.commit()
+        return {
+            "message": f"批量分解完成：{len(results)}个KPI",
+            "count": len(results),
+            "results": results,
+            "created": created_count,
+        }
+
+    # ── 单KPI模式（原有逻辑）──
+    if annual_budget is None:
+        raise HTTPException(400, "缺少必要参数: annual_budget")
 
     kpi = db.query(KPIDefinition).filter(KPIDefinition.id == kpi_id).first()
     if not kpi: