diff --git a/backend/src/main/java/com/designhub/service/AnalyticsService.java b/backend/src/main/java/com/designhub/service/AnalyticsService.java
index 28cd61f..1b27453 100644
--- a/backend/src/main/java/com/designhub/service/AnalyticsService.java
+++ b/backend/src/main/java/com/designhub/service/AnalyticsService.java
@@ -263,45 +263,53 @@ public class AnalyticsService {
      * 构建趋势数据
      */
     private List<DemandStatisticsVO.TrendData> buildTrendData(List<Task> tasks, String dateRange) {
-        Map<String, List<Task>> tasksByDate = new LinkedHashMap<>();
-        
         // 根据dateRange生成日期范围
         int days = "week".equals(dateRange) ? 7 : "month".equals(dateRange) ? 30 : 90;
         LocalDate endDate = LocalDate.now();
         
+        // 初始化日期范围
+        Map<String, Integer> demandCountByDate = new LinkedHashMap<>();
+        Map<String, Integer> completedCountByDate = new LinkedHashMap<>();
+        Map<String, BigDecimal> scoreUsedByDate = new LinkedHashMap<>();
+        
         for (int i = days - 1; i >= 0; i--) {
             LocalDate date = endDate.minusDays(i);
-            tasksByDate.put(date.format(DateTimeFormatter.ISO_LOCAL_DATE), new ArrayList<>());
+            String dateKey = date.format(DateTimeFormatter.ISO_LOCAL_DATE);
+            demandCountByDate.put(dateKey, 0);
+            completedCountByDate.put(dateKey, 0);
+            scoreUsedByDate.put(dateKey, BigDecimal.ZERO);
         }
 
-        // 将任务按日期分组
+        // 统计需求数量（按创建时间）
         for (Task task : tasks) {
-            String dateKey = task.getCreateTime().toLocalDate().format(DateTimeFormatter.ISO_LOCAL_DATE);
-            if (tasksByDate.containsKey(dateKey)) {
-                tasksByDate.get(dateKey).add(task);
+            String createDateKey = task.getCreateTime().toLocalDate().format(DateTimeFormatter.ISO_LOCAL_DATE);
+            if (demandCountByDate.containsKey(createDateKey)) {
+                demandCountByDate.merge(createDateKey, 1, Integer::sum);
+                // 积分按创建日期统计
+                if (task.getScore() != null) {
+                    scoreUsedByDate.merge(createDateKey, task.getScore(), BigDecimal::add);
+                }
+            }
+        }
+        
+        // 统计完成数量（按完成时间）
+        for (Task task : tasks) {
+            if ("completed".equals(task.getStatus()) && task.getCompleteTime() != null) {
+                String completeDateKey = task.getCompleteTime().toLocalDate().format(DateTimeFormatter.ISO_LOCAL_DATE);
+                if (completedCountByDate.containsKey(completeDateKey)) {
+                    completedCountByDate.merge(completeDateKey, 1, Integer::sum);
+                }
             }
         }
 
+        // 构建返回数据
         List<DemandStatisticsVO.TrendData> trendData = new ArrayList<>();
-        for (Map.Entry<String, List<Task>> entry : tasksByDate.entrySet()) {
-            List<Task> dateTasks = entry.getValue();
-            
-            int demandCount = dateTasks.size();
-            int completedCount = (int) dateTasks.stream()
-                .filter(t -> "completed".equals(t.getStatus()))
-                .count();
-            
-            // 使用 score 字段（预估积分）作为积分消耗，因为 scoreReward 字段未被使用
-            BigDecimal scoreUsed = dateTasks.stream()
-                .map(Task::getScore)
-                .filter(Objects::nonNull)
-                .reduce(BigDecimal.ZERO, BigDecimal::add);
-
+        for (String dateKey : demandCountByDate.keySet()) {
             trendData.add(DemandStatisticsVO.TrendData.builder()
-                .date(entry.getKey())
-                .demandCount(demandCount)
-                .completedCount(completedCount)
-                .scoreUsed(scoreUsed)
+                .date(dateKey)
+                .demandCount(demandCountByDate.get(dateKey))
+                .completedCount(completedCountByDate.get(dateKey))
+                .scoreUsed(scoreUsedByDate.get(dateKey))
                 .build());
         }