diff --git a/internal/handler/streak_handler.go b/internal/handler/streak_handler.go
index fd1d588..8360b4e 100644
--- a/internal/handler/streak_handler.go
+++ b/internal/handler/streak_handler.go
@@ -66,8 +66,27 @@ func (h *StreakHandler) RecalculateStreak(c *gin.Context) {
 	api.Success(c, streakInfo)
 }
 
+// GetContributionData handles GET /api/v1/user/streak/contribution
+// Returns daily contribution data for heat map
+func (h *StreakHandler) GetContributionData(c *gin.Context) {
+	userID, exists := c.Get("user_id")
+	if !exists {
+		api.Unauthorized(c, "User not authenticated")
+		return
+	}
+
+	contributionData, err := h.streakService.GetContributionData(userID.(uint))
+	if err != nil {
+		api.InternalError(c, "Failed to get contribution data: "+err.Error())
+		return
+	}
+
+	api.Success(c, contributionData)
+}
+
 // RegisterRoutes registers streak-related routes
 func (h *StreakHandler) RegisterRoutes(rg *gin.RouterGroup) {
 	rg.GET("/user/streak", h.GetStreak)
 	rg.POST("/user/streak/recalculate", h.RecalculateStreak)
+	rg.GET("/user/streak/contribution", h.GetContributionData)
 }
diff --git a/internal/models/user_streak.go b/internal/models/user_streak.go
index e2d1341..16e9dd9 100644
--- a/internal/models/user_streak.go
+++ b/internal/models/user_streak.go
@@ -29,3 +29,9 @@ type StreakInfo struct {
 	HasRecordToday  bool   `json:"has_record_today"`  // 今天是否已记账
 	Message         string `json:"message"`           // 提示信息
 }
+
+// DailyContribution represents transaction count for a specific date
+type DailyContribution struct {
+	Date  string `json:"date"`
+	Count int    `json:"count"`
+}
diff --git a/internal/repository/streak_repository.go b/internal/repository/streak_repository.go
index c6b22e7..a055ead 100644
--- a/internal/repository/streak_repository.go
+++ b/internal/repository/streak_repository.go
@@ -107,3 +107,51 @@ func (r *StreakRepository) GetTransactionDatesInRange(userID uint, startDate, en
 
 	return dates, nil
 }
+
+// GetDailyContribution returns daily transaction counts in a date range
+func (r *StreakRepository) GetDailyContribution(userID uint, startDate, endDate time.Time) ([]models.DailyContribution, error) {
+	var results []models.DailyContribution
+
+	// SQLite uses strftime, MySQL/Postgres uses DATE()
+	// Using a more generic approach compatible with SQLite (which is likely used locally)
+	// For production readiness with multiple DBs, raw SQL might be safer or check dialect
+
+	rows, err := r.db.Model(&models.Transaction{}).
+		Select("DATE(transaction_date) as date, COUNT(*) as count").
+		Where("user_id = ? AND transaction_date >= ? AND transaction_date <= ?", userID, startDate, endDate).
+		Group("DATE(transaction_date)").
+		Order("date ASC").
+		Rows()
+
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+
+	for rows.Next() {
+		var dateStr string // Using string to handle potential format differences
+		var count int
+		// Scan into generic types then convert
+		// Some drivers return date as time.Time, some as string/bytes
+		// Let's try scan into string first (common for DATE() function result)
+		// Or scan into interface{} to be safe
+		if err := rows.Scan(&dateStr, &count); err != nil {
+			// If string scan fails, try time.Time
+			// Unfortunately we can't rewind rows. scan is one-way.
+			// But usually drivers handle string conversion for DATE()
+			// If this fails we might need to adjust based on specific DB driver
+			return nil, err
+		}
+		// Normalize date string to YYYY-MM-DD (take first 10 chars if it includes time)
+		if len(dateStr) > 10 {
+			dateStr = dateStr[:10]
+		}
+
+		results = append(results, models.DailyContribution{
+			Date:  dateStr,
+			Count: count,
+		})
+	}
+
+	return results, nil
+}
diff --git a/internal/service/streak_service.go b/internal/service/streak_service.go
index d02dcb1..e35738b 100644
--- a/internal/service/streak_service.go
+++ b/internal/service/streak_service.go
@@ -241,3 +241,11 @@ func (s *StreakService) CheckAndResetStreak(userID uint) error {
 
 	return nil
 }
+
+// GetContributionData returns daily transaction counts for the past year
+func (s *StreakService) GetContributionData(userID uint) ([]models.DailyContribution, error) {
+	now := time.Now()
+	startDate := now.AddDate(-1, 0, 0) // 1 year ago
+
+	return s.repo.GetDailyContribution(userID, startDate, now)
+}