diff --git a/src/main/java/edu/whut/smilepicturebackend/service/impl/PictureServiceImpl.java b/src/main/java/edu/whut/smilepicturebackend/service/impl/PictureServiceImpl.java
index de18835..10b7f51 100644
--- a/src/main/java/edu/whut/smilepicturebackend/service/impl/PictureServiceImpl.java
+++ b/src/main/java/edu/whut/smilepicturebackend/service/impl/PictureServiceImpl.java
@@ -619,15 +619,16 @@ public class PictureServiceImpl extends ServiceImpl<PictureMapper, Picture>
             ThrowUtils.throwIf(!hasPermission, ErrorCode.NO_AUTH_ERROR);
         }
 
-        // 把查询条件序列化成 JSON
-        String queryJson = JSONUtil.toJsonStr(Map.of(
+        Map<String, Object> params = Map.of(
                 "spaceId", spaceId == null ? "public" : spaceId,
-                "category", queryRequest.getCategory(),
-                "tags", queryRequest.getTags(),
-                "searchText", queryRequest.getSearchText(),
+                "category", Optional.ofNullable(queryRequest.getCategory()).orElse(""),
+                "tags", Optional.ofNullable(queryRequest.getTags()).orElse(Collections.emptyList()),
+                "searchText", Optional.ofNullable(queryRequest.getSearchText()).orElse(""),
                 "current", current,
                 "size", size
-        ));
+        );
+        // 把查询条件序列化成 JSON
+        String queryJson = JSONUtil.toJsonStr(params);
 
         // 计算 MD5 作为哈希（也可用 SHA256）
         String hash = DigestUtil.md5Hex(queryJson);