diff --git a/src/main/java/com/sztzjy/linkCommerce/service/impl/HardwareCostStepFourServiceImpl.java b/src/main/java/com/sztzjy/linkCommerce/service/impl/HardwareCostStepFourServiceImpl.java
index 2ec04d9..80d4d83 100644
--- a/src/main/java/com/sztzjy/linkCommerce/service/impl/HardwareCostStepFourServiceImpl.java
+++ b/src/main/java/com/sztzjy/linkCommerce/service/impl/HardwareCostStepFourServiceImpl.java
@@ -38,19 +38,19 @@ public class HardwareCostStepFourServiceImpl implements HardwareCostStepFourServ
         String optimizationPlan = request == null ? "" : StringUtils.trimToEmpty(request.getOptimizationPlan());
         if (StringUtils.isBlank(smallBatchChartUrl) || StringUtils.isBlank(largeBatchChartUrl)) {
             throw new ServiceException(HttpStatus.BAD_REQUEST,
-                    "Please upload both small-batch and mass-production cost structure charts.");
+                    "请分别上传小批量试产和大批量量产成本结构图。");
         }
         if (StringUtils.isBlank(optimizationPlan)) {
-            throw new ServiceException(HttpStatus.BAD_REQUEST, "Please enter the cost optimisation decision.");
+            throw new ServiceException(HttpStatus.BAD_REQUEST, "请填写成本优化方案。");
         }
         if (optimizationPlan.length() > MAX_OPTIMIZATION_PLAN_LENGTH) {
             throw new ServiceException(HttpStatus.BAD_REQUEST,
-                    "The cost optimisation decision cannot exceed " + MAX_OPTIMIZATION_PLAN_LENGTH + " characters.");
+                    "成本优化方案不能超过 " + MAX_OPTIMIZATION_PLAN_LENGTH + " 字。");
         }
 
         HardwareCostStepFourValidationResult result = new HardwareCostStepFourValidationResult();
         result.setValid(true);
-        result.setMessage("Cost structure charts and optimisation decision have been validated.");
+        result.setMessage("成本结构图与成本优化方案校验通过。");
         return result;
     }
 
@@ -58,22 +58,22 @@ public class HardwareCostStepFourServiceImpl implements HardwareCostStepFourServ
         TeachingClassStudent membership = teachingClassStudentMapper.selectActiveByStudentUserId(user.getUserId());
         TrainingTask task = trainingTaskMapper.selectByTaskKey(TASK_KEY);
         if (membership == null || task == null) {
-            throw new ServiceException(HttpStatus.BAD_REQUEST, "Current training task context was not found.");
+            throw new ServiceException(HttpStatus.BAD_REQUEST, "未找到当前实训任务信息。");
         }
         StudentTrainingAnswer answer = studentTrainingAnswerMapper.selectByStudentClassAndTask(
                 user.getUserId(), membership.getTeachingClassId(), task.getId());
         if (answer == null || StringUtils.isAnyBlank(answer.getStep1Answer(), answer.getStep2Answer(), answer.getStep3Answer())) {
             throw new ServiceException(HttpStatus.BAD_REQUEST,
-                    "Please save the first three cost-estimation steps before completing Step 4.");
+                    "请先完成并保存前 3 步成本估算内容，再完成第 4 步。");
         }
     }
 
     private void requireStudent(JwtUser user) {
         if (user == null || StringUtils.isBlank(user.getUserId())) {
-            throw new ServiceException(HttpStatus.UNAUTHORIZED, "Please log in first.");
+            throw new ServiceException(HttpStatus.UNAUTHORIZED, "请先登录后再操作。");
         }
         if (user.getRoleId() != 4) {
-            throw new ServiceException(HttpStatus.FORBIDDEN, "Only students can validate training answers.");
+            throw new ServiceException(HttpStatus.FORBIDDEN, "仅学生可以校验实训答案。");
         }
     }
 }
diff --git a/src/test/java/com/sztzjy/linkCommerce/service/impl/HardwareCostStepFourServiceImplTest.java b/src/test/java/com/sztzjy/linkCommerce/service/impl/HardwareCostStepFourServiceImplTest.java
new file mode 100644
index 0000000..4f697e5
--- /dev/null
+++ b/src/test/java/com/sztzjy/linkCommerce/service/impl/HardwareCostStepFourServiceImplTest.java
@@ -0,0 +1,66 @@
+package com.sztzjy.linkCommerce.service.impl;
+
+import com.sztzjy.linkCommerce.config.security.JwtUser;
+import com.sztzjy.linkCommerce.entity.StudentTrainingAnswer;
+import com.sztzjy.linkCommerce.entity.TeachingClassStudent;
+import com.sztzjy.linkCommerce.entity.TrainingTask;
+import com.sztzjy.linkCommerce.entity.dto.HardwareCostStepFourValidationRequest;
+import com.sztzjy.linkCommerce.entity.dto.HardwareCostStepFourValidationResult;
+import com.sztzjy.linkCommerce.mapper.StudentTrainingAnswerMapper;
+import com.sztzjy.linkCommerce.mapper.TeachingClassStudentMapper;
+import com.sztzjy.linkCommerce.mapper.TrainingTaskMapper;
+import org.junit.jupiter.api.Test;
+import org.springframework.test.util.ReflectionTestUtils;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+import static org.mockito.ArgumentMatchers.anyString;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
+
+class HardwareCostStepFourServiceImplTest {
+    @Test
+    void reportsChineseValidationSuccessAfterChartsAndOptimizationPlanAreComplete() {
+        HardwareCostStepFourValidationResult result = serviceWithCompletedPreviousSteps().validate(completedRequest(), student());
+
+        assertTrue(result.isValid());
+        assertEquals("成本结构图与成本优化方案校验通过。", result.getMessage());
+    }
+
+    private HardwareCostStepFourServiceImpl serviceWithCompletedPreviousSteps() {
+        HardwareCostStepFourServiceImpl service = new HardwareCostStepFourServiceImpl();
+        TeachingClassStudentMapper memberships = mock(TeachingClassStudentMapper.class);
+        TrainingTaskMapper tasks = mock(TrainingTaskMapper.class);
+        StudentTrainingAnswerMapper answers = mock(StudentTrainingAnswerMapper.class);
+        TeachingClassStudent membership = new TeachingClassStudent();
+        membership.setTeachingClassId("class-1");
+        TrainingTask task = new TrainingTask();
+        task.setId("task-16");
+        StudentTrainingAnswer answer = new StudentTrainingAnswer();
+        answer.setStep1Answer("{}");
+        answer.setStep2Answer("{}");
+        answer.setStep3Answer("{}");
+        when(memberships.selectActiveByStudentUserId("student-1")).thenReturn(membership);
+        when(tasks.selectByTaskKey("hardware-cost")).thenReturn(task);
+        when(answers.selectByStudentClassAndTask(anyString(), anyString(), anyString())).thenReturn(answer);
+        ReflectionTestUtils.setField(service, "teachingClassStudentMapper", memberships);
+        ReflectionTestUtils.setField(service, "trainingTaskMapper", tasks);
+        ReflectionTestUtils.setField(service, "studentTrainingAnswerMapper", answers);
+        return service;
+    }
+
+    private HardwareCostStepFourValidationRequest completedRequest() {
+        HardwareCostStepFourValidationRequest request = new HardwareCostStepFourValidationRequest();
+        request.setSmallBatchChartUrl("/file/small-batch.png");
+        request.setLargeBatchChartUrl("/file/large-batch.png");
+        request.setOptimizationPlan("优先优化高成本元器件，并保留关键性能冗余。");
+        return request;
+    }
+
+    private JwtUser student() {
+        JwtUser user = new JwtUser();
+        user.setUserId("student-1");
+        user.setRoleId(4);
+        return user;
+    }
+}