diff --git a/backend/app/api/maps.py b/backend/app/api/maps.py
index 04043a50..e9e6703a 100644
--- a/backend/app/api/maps.py
+++ b/backend/app/api/maps.py
@@ -66,6 +66,16 @@ def list_maps(db: Session = Depends(get_db)):
 
 @router.post("")
 def create_map(data: dict, db: Session = Depends(get_db)):
+    # 空白地图默认四层空结构（避免dimensions=NULL导致加载报错）
+    if "dimensions" not in data or data.get("dimensions") is None:
+        data = {**data, "dimensions": [
+            {"key": "finance", "name": "财务层", "icon": "💰", "color": "#F56C6C", "objectives": []},
+            {"key": "customer", "name": "客户层", "icon": "👥", "color": "#409EFF", "objectives": []},
+            {"key": "process", "name": "流程层", "icon": "⚙️", "color": "#67C23A", "objectives": []},
+            {"key": "learning", "name": "学习层", "icon": "📚", "color": "#E6A23C", "objectives": []},
+        ]}
+    if "canvas_data" not in data or data.get("canvas_data") is None:
+        data = {**data, "canvas_data": {"connections": []}}
     m = StrategicMap(**data)
     db.add(m)
     db.commit()
@@ -283,6 +293,7 @@ def _sync_map_objectives(m, db):
     dims = m.dimensions
     if isinstance(dims, str):
         dims = json.loads(dims)
+    dims = dims or []
     for dim in dims:
         for i, obj in enumerate(dim.get("objectives", [])):
             mo = MapObjective(
@@ -306,6 +317,7 @@ def _merge_map_objectives(m, db):
     dims = m.dimensions
     if isinstance(dims, str):
         dims = json.loads(dims)
+    dims = dims or []
     # 按dimension_key分组
     from collections import defaultdict
     grouped = defaultdict(list)
@@ -347,6 +359,7 @@ def get_map_review(map_id: int, level: Optional[str] = None, db: Session = Depen
     dims = m.dimensions
     if isinstance(dims, str):
         dims = json.loads(dims)
+    dims = dims or []  # NULL容错
 
     # 收集所有KPI code
     all_kpi_codes = set()