diff --git a/apollo-biz/src/main/java/com/ctrip/framework/apollo/biz/service/AppNamespaceService.java b/apollo-biz/src/main/java/com/ctrip/framework/apollo/biz/service/AppNamespaceService.java
index b31a94311bfb4e56b5a838969b4694216a8b755f..4a78f53aa078e9d083c84cc03375cdebf8cc56c6 100644
--- a/apollo-biz/src/main/java/com/ctrip/framework/apollo/biz/service/AppNamespaceService.java
+++ b/apollo-biz/src/main/java/com/ctrip/framework/apollo/biz/service/AppNamespaceService.java
@@ -131,6 +131,12 @@ public class AppNamespaceService {
     List<Cluster> clusters = clusterService.findParentClusters(appId);
 
     for (Cluster cluster : clusters) {
+
+      // in case there is some dirty data, e.g. public namespace deleted in other app and now created in this app
+      if (!namespaceService.isNamespaceUnique(appId, cluster.getName(), namespaceName)) {
+        continue;
+      }
+
       Namespace namespace = new Namespace();
       namespace.setClusterName(cluster.getName());
       namespace.setAppId(appId);
diff --git a/apollo-configservice/src/main/java/com/ctrip/framework/apollo/configservice/service/AppNamespaceServiceWithCache.java b/apollo-configservice/src/main/java/com/ctrip/framework/apollo/configservice/service/AppNamespaceServiceWithCache.java
index 90a6976ea41e26ed24610f15b1f5bf685c8c2037..e0f7479b7d0430d63100a93d093361c9d16ec848 100644
--- a/apollo-configservice/src/main/java/com/ctrip/framework/apollo/configservice/service/AppNamespaceServiceWithCache.java
+++ b/apollo-configservice/src/main/java/com/ctrip/framework/apollo/configservice/service/AppNamespaceServiceWithCache.java
@@ -247,7 +247,11 @@ public class AppNamespaceServiceWithCache implements InitializingBean {
       }
       appNamespaceCache.remove(assembleAppNamespaceKey(deleted));
       if (deleted.isPublic()) {
-        publicAppNamespaceCache.remove(deleted.getName());
+        AppNamespace publicAppNamespace = publicAppNamespaceCache.get(deleted.getName());
+        // in case there is some dirty data, e.g. public namespace deleted in some app and now created in another app
+        if (publicAppNamespace == deleted) {
+          publicAppNamespaceCache.remove(deleted.getName());
+        }
       }
       logger.info("Found AppNamespace deleted, {}", deleted);
     }