diff --git a/src/main/java/cn/teammodel/model/entity/Evaluation.java b/src/main/java/cn/teammodel/model/entity/Evaluation.java
index 1547dd1..fc6bcaf 100644
--- a/src/main/java/cn/teammodel/model/entity/Evaluation.java
+++ b/src/main/java/cn/teammodel/model/entity/Evaluation.java
@@ -3,8 +3,8 @@ package cn.teammodel.model.entity;
 import com.azure.spring.data.cosmos.core.mapping.Container;
 import com.azure.spring.data.cosmos.core.mapping.GeneratedValue;
 import com.azure.spring.data.cosmos.core.mapping.PartitionKey;
+import com.fasterxml.jackson.annotation.JsonInclude;
 import lombok.Data;
-import lombok.ToString;
 import org.springframework.data.annotation.Id;
 
 import java.util.List;
@@ -16,7 +16,7 @@ import java.util.List;
  */
 @Container(containerName = "School")
 @Data
-@ToString
+@JsonInclude(JsonInclude.Include.NON_NULL)
 public class Evaluation {
     @Id
     @GeneratedValue
diff --git a/src/main/java/cn/teammodel/model/entity/EvaluationTreeNode.java b/src/main/java/cn/teammodel/model/entity/EvaluationTreeNode.java
index d71870e..4d2f0bb 100644
--- a/src/main/java/cn/teammodel/model/entity/EvaluationTreeNode.java
+++ b/src/main/java/cn/teammodel/model/entity/EvaluationTreeNode.java
@@ -1,6 +1,7 @@
 package cn.teammodel.model.entity;
 
 import com.fasterxml.jackson.annotation.JsonFormat;
+import com.fasterxml.jackson.annotation.JsonInclude;
 import com.fasterxml.jackson.annotation.JsonProperty;
 import lombok.Data;
 
@@ -8,6 +9,7 @@ import java.time.LocalDateTime;
 import java.util.List;
 
 @Data
+@JsonInclude(JsonInclude.Include.NON_NULL)
 public class EvaluationTreeNode {
     String id;
     String pid;
diff --git a/src/main/java/cn/teammodel/service/impl/EvaluationServiceImpl.java b/src/main/java/cn/teammodel/service/impl/EvaluationServiceImpl.java
index bc273a6..7748549 100644
--- a/src/main/java/cn/teammodel/service/impl/EvaluationServiceImpl.java
+++ b/src/main/java/cn/teammodel/service/impl/EvaluationServiceImpl.java
@@ -123,7 +123,6 @@ public class EvaluationServiceImpl implements EvaluationService {
         newNode.setCreateTime(LocalDateTime.now());
 
         originNodes.add(newNode);
-        evaluation.setNodes(originNodes); // 好像不需要?
         return buildTree(evaluationRepository.save(evaluation));
     }