diff --git a/src/main/java/com/github/hcsp/datatype/Light.java b/src/main/java/com/github/hcsp/datatype/Light.java
index ccfa68a..a823554 100644
--- a/src/main/java/com/github/hcsp/datatype/Light.java
+++ b/src/main/java/com/github/hcsp/datatype/Light.java
@@ -13,6 +13,10 @@ public Light(Boolean on) {
 
     // 当灯亮时返回true，灭和未知状态返回false
     public boolean isOn() {
-        return on;
+        if(on==null) {
+            return false;
+        }else{
+            return on;
+        }
     }
 }