diff --git a/src/business/room_decor/room_decor.service.ts b/src/business/room_decor/room_decor.service.ts
index 4738f80..eeeaa7b 100644
--- a/src/business/room_decor/room_decor.service.ts
+++ b/src/business/room_decor/room_decor.service.ts
@@ -83,11 +83,18 @@ export class RoomDecorService {
     if (!definition.rotation_steps.includes(rotationDegrees)) {
       throw new BadRequestException('该摆件不支持此旋转角度');
     }
+    const positionX = this.snapToGrid(placement.position_x ?? definition.default_position.x, definition.grid_size);
+    const positionY = this.snapToGrid(placement.position_y ?? definition.default_position.y, definition.grid_size);
+    if (placement.placed && !this.isWithinPlacementBounds(positionX, positionY, definition)) {
+      throw new BadRequestException(definition.placement_surface === 'wall'
+        ? '墙面挂饰只能摆放在墙面网格内'
+        : '地面家具只能摆放在地面网格内');
+    }
     const row = await this.roomDecorPlacementsService.savePlacement(userId, {
       ...placement,
       decor_id: decorId,
-      position_x: this.snapToGrid(placement.position_x, definition.grid_size),
-      position_y: this.snapToGrid(placement.position_y, definition.grid_size),
+      position_x: positionX,
+      position_y: positionY,
       scale: placement.scale ?? definition.default_scale,
       rotation_degrees: rotationDegrees,
       z_index: placement.z_index ?? definition.default_z_index,
@@ -145,6 +152,7 @@ export class RoomDecorService {
       z_index: row.z_index ?? definition?.default_z_index ?? 0,
       category: definition?.category ?? 'floor',
       placement_surface: definition?.placement_surface ?? 'floor',
+      placement_bounds: definition?.placement_bounds,
       grid_size: definition?.grid_size ?? 16,
       rotation_steps: definition?.rotation_steps ?? [0],
       stackable: definition?.stackable ?? false,
@@ -207,11 +215,15 @@ export class RoomDecorService {
     return definition?.rotation_steps.includes(rotation) ? rotation : definition?.default_rotation_degrees ?? 0;
   }
 
-  private snapToGrid(value: number | undefined, gridSize: number): number | undefined {
-    if (value === undefined) return undefined;
+  private snapToGrid(value: number, gridSize: number): number {
     return Math.round(value / gridSize) * gridSize;
   }
 
+  private isWithinPlacementBounds(x: number, y: number, definition: RoomDecorDefinition): boolean {
+    const bounds = definition.placement_bounds;
+    return x >= bounds.min_x && x <= bounds.max_x && y >= bounds.min_y && y <= bounds.max_y;
+  }
+
   private usesLegacyPlacement(row: UserRoomDecorRow) {
     const legacy = ROOM_DECOR_LEGACY_DEFAULTS[row.decor_id];
     if (!legacy) {
diff --git a/src/business/room_decor/room_decor_catalog.ts b/src/business/room_decor/room_decor_catalog.ts
index 739311a..9932491 100644
--- a/src/business/room_decor/room_decor_catalog.ts
+++ b/src/business/room_decor/room_decor_catalog.ts
@@ -4,6 +4,7 @@ export interface RoomDecorDefinition {
   item_id: string;
   category: 'floor' | 'rug' | 'wall';
   placement_surface: 'floor' | 'wall';
+  placement_bounds: RoomDecorPlacementBounds;
   grid_size: number;
   rotation_steps: number[];
   stackable: boolean;
@@ -33,6 +34,13 @@ export interface RoomDecorDefinition {
   };
 }
 
+export interface RoomDecorPlacementBounds {
+  min_x: number;
+  max_x: number;
+  min_y: number;
+  max_y: number;
+}
+
 export interface RoomDecorLegacyDefault {
   scale: number;
   default_position: {
@@ -48,6 +56,18 @@ export const ROOM_DECOR_FLOOR_RUG_DEFAULT_SCALE = 1.0;
 export const ROOM_DECOR_WALL_DECOR_DEFAULT_SCALE = 0.04;
 export const ROOM_DECOR_LEGACY_BED_MAX_SCALE = 0.35;
 export const ROOM_DECOR_LEGACY_WALL_DECOR_SCALES = [0.7, 0.18];
+export const ROOM_DECOR_FLOOR_PLACEMENT_BOUNDS: RoomDecorPlacementBounds = {
+  min_x: -426,
+  max_x: 426,
+  min_y: -176,
+  max_y: 212,
+};
+export const ROOM_DECOR_WALL_PLACEMENT_BOUNDS: RoomDecorPlacementBounds = {
+  min_x: -378,
+  max_x: 378,
+  min_y: -258,
+  max_y: -192,
+};
 
 export const ROOM_DECOR_LEGACY_DEFAULTS: Record<string, RoomDecorLegacyDefault> = {
   whale_floor_rug: {
@@ -99,6 +119,7 @@ export const ROOM_DECOR_DEFINITIONS: RoomDecorDefinition[] = [
     name: '鲸浪地毯',
     category: 'rug',
     placement_surface: 'floor',
+    placement_bounds: ROOM_DECOR_FLOOR_PLACEMENT_BOUNDS,
     grid_size: 16,
     rotation_steps: [0],
     stackable: false,
@@ -116,6 +137,7 @@ export const ROOM_DECOR_DEFINITIONS: RoomDecorDefinition[] = [
     name: '鲸语记忆板',
     category: 'wall',
     placement_surface: 'wall',
+    placement_bounds: ROOM_DECOR_WALL_PLACEMENT_BOUNDS,
     grid_size: 16,
     rotation_steps: [0],
     stackable: false,
@@ -132,6 +154,7 @@ export const ROOM_DECOR_DEFINITIONS: RoomDecorDefinition[] = [
     name: '鲸尾暖灯',
     category: 'floor',
     placement_surface: 'floor',
+    placement_bounds: ROOM_DECOR_FLOOR_PLACEMENT_BOUNDS,
     grid_size: 16,
     rotation_steps: [0, 90, 180, 270],
     stackable: false,
@@ -151,6 +174,7 @@ export const ROOM_DECOR_DEFINITIONS: RoomDecorDefinition[] = [
     name: '船舱小床',
     category: 'floor',
     placement_surface: 'floor',
+    placement_bounds: ROOM_DECOR_FLOOR_PLACEMENT_BOUNDS,
     grid_size: 16,
     rotation_steps: [0, 90, 180, 270],
     stackable: false,
@@ -170,6 +194,7 @@ export const ROOM_DECOR_DEFINITIONS: RoomDecorDefinition[] = [
     name: '海浪低床',
     category: 'floor',
     placement_surface: 'floor',
+    placement_bounds: ROOM_DECOR_FLOOR_PLACEMENT_BOUNDS,
     grid_size: 16,
     rotation_steps: [0, 90, 180, 270],
     stackable: false,
@@ -189,6 +214,7 @@ export const ROOM_DECOR_DEFINITIONS: RoomDecorDefinition[] = [
     name: '鲸尾床头床',
     category: 'floor',
     placement_surface: 'floor',
+    placement_bounds: ROOM_DECOR_FLOOR_PLACEMENT_BOUNDS,
     grid_size: 16,
     rotation_steps: [0, 90, 180, 270],
     stackable: false,
@@ -208,6 +234,7 @@ export const ROOM_DECOR_DEFINITIONS: RoomDecorDefinition[] = [
     name: '程序员鲸书架',
     category: 'floor',
     placement_surface: 'floor',
+    placement_bounds: ROOM_DECOR_FLOOR_PLACEMENT_BOUNDS,
     grid_size: 16,
     rotation_steps: [0, 90, 180, 270],
     stackable: false,
@@ -227,6 +254,7 @@ export const ROOM_DECOR_DEFINITIONS: RoomDecorDefinition[] = [
     name: 'BUG特性徽章',
     category: 'wall',
     placement_surface: 'wall',
+    placement_bounds: ROOM_DECOR_WALL_PLACEMENT_BOUNDS,
     grid_size: 16,
     rotation_steps: [0],
     stackable: false,
@@ -244,6 +272,7 @@ export const ROOM_DECOR_DEFINITIONS: RoomDecorDefinition[] = [
     name: '佛系学习徽章',
     category: 'wall',
     placement_surface: 'wall',
+    placement_bounds: ROOM_DECOR_WALL_PLACEMENT_BOUNDS,
     grid_size: 16,
     rotation_steps: [0],
     stackable: false,
@@ -261,6 +290,7 @@ export const ROOM_DECOR_DEFINITIONS: RoomDecorDefinition[] = [
     name: '已经在做徽章',
     category: 'wall',
     placement_surface: 'wall',
+    placement_bounds: ROOM_DECOR_WALL_PLACEMENT_BOUNDS,
     grid_size: 16,
     rotation_steps: [0],
     stackable: false,