diff --git a/storage/src/main/java/com/zfoo/storage/convert/JsonToMapConverter.java b/storage/src/main/java/com/zfoo/storage/convert/JsonToMapConverter.java
index c209bd04..b0a41e69 100644
--- a/storage/src/main/java/com/zfoo/storage/convert/JsonToMapConverter.java
+++ b/storage/src/main/java/com/zfoo/storage/convert/JsonToMapConverter.java
@@ -14,6 +14,7 @@
 package com.zfoo.storage.convert;
 
 import com.zfoo.protocol.util.JsonUtils;
+import com.zfoo.protocol.util.StringUtils;
 import org.springframework.core.convert.TypeDescriptor;
 import org.springframework.core.convert.converter.ConditionalGenericConverter;
 
@@ -38,6 +39,9 @@ public class JsonToMapConverter implements ConditionalGenericConverter {
     @Override
     public Object convert(Object source, TypeDescriptor sourceType, TypeDescriptor targetType) {
         String content = (String) source;
+        if (StringUtils.isBlank(content)) {
+            return Collections.emptyMap();
+        }
         return JsonUtils.string2Map(content, targetType.getMapKeyTypeDescriptor().getType(), targetType.getMapValueTypeDescriptor().getType());
     }
 }
diff --git a/storage/src/main/java/com/zfoo/storage/convert/JsonToObjectConverter.java b/storage/src/main/java/com/zfoo/storage/convert/JsonToObjectConverter.java
index ff696a1a..673f7a5a 100644
--- a/storage/src/main/java/com/zfoo/storage/convert/JsonToObjectConverter.java
+++ b/storage/src/main/java/com/zfoo/storage/convert/JsonToObjectConverter.java
@@ -15,6 +15,7 @@ package com.zfoo.storage.convert;
 
 import com.zfoo.protocol.util.JsonUtils;
 import com.zfoo.protocol.util.ReflectionUtils;
+import com.zfoo.protocol.util.StringUtils;
 import org.springframework.core.convert.TypeDescriptor;
 import org.springframework.core.convert.converter.ConditionalGenericConverter;
 
@@ -58,6 +59,9 @@ public class JsonToObjectConverter implements ConditionalGenericConverter {
     @Override
     public Object convert(Object source, TypeDescriptor sourceType, TypeDescriptor targetType) {
         String content = (String) source;
+        if (StringUtils.isBlank(content)) {
+            return null;
+        }
         return JsonUtils.string2Object(content, targetType.getType());
     }
 }
diff --git a/storage/src/test/resources/excel/StudentResource.xlsx b/storage/src/test/resources/excel/StudentResource.xlsx
index 88dda96a..ec1367e6 100644
Binary files a/storage/src/test/resources/excel/StudentResource.xlsx and b/storage/src/test/resources/excel/StudentResource.xlsx differ