diff --git a/apollo-client/src/main/java/com/ctrip/framework/apollo/spring/property/PlaceholderHelper.java b/apollo-client/src/main/java/com/ctrip/framework/apollo/spring/property/PlaceholderHelper.java
index 39c587c27e7dc61da0ae9ae13034e40a0a87778f..21a9d0348717c4144d3134845fe7fe84d96e4454 100644
--- a/apollo-client/src/main/java/com/ctrip/framework/apollo/spring/property/PlaceholderHelper.java
+++ b/apollo-client/src/main/java/com/ctrip/framework/apollo/spring/property/PlaceholderHelper.java
@@ -66,7 +66,7 @@ public class PlaceholderHelper {
   public Set<String> extractPlaceholderKeys(String propertyString) {
     Set<String> placeholderKeys = Sets.newHashSet();
 
-    if (Objects.isNull(propertyString) || (!isNormalizedPlaceholder(propertyString) && !isExpressionWithPlaceholder(propertyString))) {
+    if (Strings.isNullOrEmpty(propertyString) || (!isNormalizedPlaceholder(propertyString) && !isExpressionWithPlaceholder(propertyString))) {
       return placeholderKeys;
     }