diff --git a/backend/controller/agent.go b/backend/controller/agent.go
index 01da678..2f738da 100644
--- a/backend/controller/agent.go
+++ b/backend/controller/agent.go
@@ -64,6 +64,8 @@ func (h *AgentHandler) ReceiveReport(c *gin.Context) {
 			reportTime = t
 		}
 	}
+	// Agent 上报时间统一存储为 UTC，避免 SQLite 按带时区文本比较时误判。 // Logan.Li
+	reportTime = reportTime.UTC()
 
 	matchedServer, matchIP, assetMatched := h.resolveAgentAsset(req.Hostname, req.IP, c.ClientIP())
 	canonicalHostname := req.Hostname
@@ -260,7 +262,8 @@ func (h *AgentHandler) writeHotMetric(c *gin.Context, key string, value float64,
 // GET /api/v1/agent/latest
 func (h *AgentHandler) GetLatestReports(c *gin.Context) {
 	var results []model.AgentLatestResponse
-	threeMinAgo := time.Now().Add(-3 * time.Minute)
+	// 查询边界与 Agent 上报的 UTC 时间保持一致。 // Logan.Li
+	threeMinAgo := time.Now().UTC().Add(-3 * time.Minute)
 	// 以 servers 表为主，LEFT JOIN 最近 3 分钟内的 Agent 上报
 	// 未装 Agent 的主机也会显示（agent_status='not_installed'），打破"不显示→无法安装"的循环
 	h.db.Raw(`
@@ -394,7 +397,8 @@ func (h *AgentHandler) GetHostHistory(c *gin.Context) {
 	}
 
 	var reports []model.AgentReport
-	h.db.Where("hostname = ? AND report_time >= ? AND report_time <= ?", hostname, since, until).
+	// SQLite 会按时间文本比较，查询边界需统一转换为 UTC。 // Logan.Li
+	h.db.Where("hostname = ? AND report_time >= ? AND report_time <= ?", hostname, since.UTC(), until.UTC()).
 		Order("report_time ASC").
 		Find(&reports)
 
@@ -479,7 +483,8 @@ func (h *AgentHandler) aggregateFromReports(req model.AggregateReq) (int64, erro
 
 	for _, iv := range intervals {
 		lookback := iv.duration * 200
-		since := time.Now().Add(-lookback)
+		// 本地 SQLite 模式下使用 UTC 边界查询 Agent 报告。 // Logan.Li
+		since := time.Now().UTC().Add(-lookback)
 		var reports []model.AgentReport
 		if err := h.db.Where("hostname = ? AND report_time >= ?", req.Hostname, since).
 			Order("report_time ASC").Find(&reports).Error; err != nil {
diff --git a/backend/controller/agent_report_test.go b/backend/controller/agent_report_test.go
index e0e35c9..a35c374 100644
--- a/backend/controller/agent_report_test.go
+++ b/backend/controller/agent_report_test.go
@@ -2,9 +2,11 @@ package controller
 
 import (
 	"bytes"
+	"encoding/json"
 	"net/http"
 	"net/http/httptest"
 	"testing"
+	"time"
 
 	"ezops/model"
 
@@ -76,3 +78,68 @@ func TestReceiveReportMatchesExistingAssetByIP(t *testing.T) {
 		t.Fatalf("上报后产生重复资产: count=%d", serverCount)
 	}
 }
+
+func TestGetLatestReportsUsesUTCTimeBoundary(t *testing.T) {
+	gin.SetMode(gin.TestMode)
+	db, err := gorm.Open(sqlite.Open("file:agent_latest_utc?mode=memory&cache=shared"), &gorm.Config{
+		Logger: gormlogger.Default.LogMode(gormlogger.Silent),
+	})
+	if err != nil {
+		t.Fatalf("打开测试数据库失败: %v", err)
+	}
+	if err := db.AutoMigrate(&model.Server{}, &model.AgentReport{}); err != nil {
+		t.Fatalf("迁移测试表失败: %v", err)
+	}
+	if err := db.Exec("CREATE TABLE asset_regions (id INTEGER PRIMARY KEY, name TEXT)").Error; err != nil {
+		t.Fatalf("创建区域测试表失败: %v", err)
+	}
+
+	server := model.Server{
+		Hostname:     "c-redis-cluster-3",
+		IP:           "172.19.16.59",
+		AgentVersion: "v2.1.0",
+		AgentStatus:  "online",
+		DiskUsage:    5.56,
+	}
+	if err := db.Create(&server).Error; err != nil {
+		t.Fatalf("创建测试资产失败: %v", err)
+	}
+	// 模拟 Agent 以 UTC 上报，同时应用运行在 UTC+8 时区。 // Logan.Li
+	report := model.AgentReport{
+		Hostname:   server.Hostname,
+		CPUUsage:   12.5,
+		MemUsage:   39.7,
+		CPUCores:   4,
+		ReportTime: time.Now().UTC().Add(-time.Minute),
+	}
+	if err := db.Create(&report).Error; err != nil {
+		t.Fatalf("创建 Agent 报告失败: %v", err)
+	}
+
+	originalLocal := time.Local
+	time.Local = time.FixedZone("UTC+8", 8*60*60)
+	defer func() { time.Local = originalLocal }()
+
+	recorder := httptest.NewRecorder()
+	c, _ := gin.CreateTestContext(recorder)
+	c.Request = httptest.NewRequest(http.MethodGet, "/api/v1/agent/latest", nil)
+	NewAgentHandler(db, nil, nil).GetLatestReports(c)
+	if recorder.Code != http.StatusOK {
+		t.Fatalf("查询返回码 = %d, body=%s", recorder.Code, recorder.Body.String())
+	}
+
+	var response struct {
+		Code int                         `json:"code"`
+		Data []model.AgentLatestResponse `json:"data"`
+	}
+	if err := json.Unmarshal(recorder.Body.Bytes(), &response); err != nil {
+		t.Fatalf("解析响应失败: %v", err)
+	}
+	if len(response.Data) != 1 {
+		t.Fatalf("主机数量 = %d, body=%s", len(response.Data), recorder.Body.String())
+	}
+	got := response.Data[0]
+	if got.AgentStatus != "online" || got.CPUUsage != 12.5 || got.MemUsage != 39.7 {
+		t.Fatalf("最新指标未命中: status=%q cpu=%.1f mem=%.1f", got.AgentStatus, got.CPUUsage, got.MemUsage)
+	}
+}
diff --git a/backend/controller/agent_task.go b/backend/controller/agent_task.go
index 0e93425..a81f8f1 100644
--- a/backend/controller/agent_task.go
+++ b/backend/controller/agent_task.go
@@ -167,9 +167,9 @@ func (h *AgentTaskHandler) QuickSetupRules(c *gin.Context) {
 		Pluck("hostname", &onlineHosts)
 
 	if len(onlineHosts) == 0 {
-		// 如果没有在线主机，尝试从 agent_reports 中获取最近 3 分钟活跃的主机名
+		// 如果没有在线主机，使用 UTC 边界从 Agent 报告中查找最近 3 分钟活跃主机。 // Logan.Li
 		h.db.Model(&model.AgentReport{}).
-			Where("report_time >= ?", time.Now().Add(-3*time.Minute)).
+			Where("report_time >= ?", time.Now().UTC().Add(-3*time.Minute)).
 			Distinct("hostname").
 			Pluck("hostname", &onlineHosts)
 	}
diff --git a/backend/controller/alert_engine.go b/backend/controller/alert_engine.go
index 57866ec..6b71c81 100644
--- a/backend/controller/alert_engine.go
+++ b/backend/controller/alert_engine.go
@@ -227,7 +227,8 @@ func (e *AlertEngine) checkOfflineAlerts() {
 	e.db.Select("ip, hostname").Group("ip").Find(&servers)
 
 	// 收集所有 agent_reports 中活跃上报的主机名（最近 3 分钟内有上报）
-	threeMinAgo := time.Now().Add(-offlineThreshold)
+	// Agent 报告统一使用 UTC，避免 SQLite 时区文本比较导致误报离线。 // Logan.Li
+	threeMinAgo := time.Now().UTC().Add(-offlineThreshold)
 
 	var activeHostnames []string
 	e.db.Model(&model.AgentReport{}).
diff --git a/backend/controller/dashboard.go b/backend/controller/dashboard.go
index 103297c..89fbf7d 100644
--- a/backend/controller/dashboard.go
+++ b/backend/controller/dashboard.go
@@ -366,8 +366,8 @@ func (h *DashboardHandler) GetMetrics(c *gin.Context) {
 		}
 	}
 
-	// 从 agent_reports 表查最近 N 小时的真实数据（整数分组，可用索引）
-	since := time.Now().Add(-time.Duration(hours) * time.Hour)
+	// 从 agent_reports 表按 UTC 边界查最近 N 小时的真实数据。 // Logan.Li
+	since := time.Now().UTC().Add(-time.Duration(hours) * time.Hour)
 	type avgPoint struct {
 		BucketTS int64
 		AvgCPU   float64
diff --git a/backend/pkg/aiopscontext/service.go b/backend/pkg/aiopscontext/service.go
index 3343a8c..fb0822f 100644
--- a/backend/pkg/aiopscontext/service.go
+++ b/backend/pkg/aiopscontext/service.go
@@ -144,7 +144,8 @@ func (s *Service) MetricSummary(ctx context.Context, target, metric, timeRange s
 	}
 	since := sinceByRange(timeRange, time.Hour)
 	var reports []model.AgentReport
-	if err := s.db.WithContext(ctx).Where("hostname = ? AND report_time >= ?", hostname, since).
+	// Agent 指标时间统一为 UTC，确保 SQLite 按时间文本比较能命中数据。 // Logan.Li
+	if err := s.db.WithContext(ctx).Where("hostname = ? AND report_time >= ?", hostname, since.UTC()).
 		Order("report_time ASC").Limit(limit).Find(&reports).Error; err != nil {
 		return nil, err
 	}