diff --git a/internal/handler/series.go b/internal/handler/series.go
index c9ac3fe..314bc8e 100644
--- a/internal/handler/series.go
+++ b/internal/handler/series.go
@@ -89,7 +89,7 @@ func listLibrarySeriesHandler(svc *service.Container) gin.HandlerFunc {
 				writeInternalOrCanceled(c, err)
 				return
 			}
-			cards = service.SortSeriesCards(cards, sortSpec.Field, sortSpec.Order, history)
+			cards = sortRemoteSeriesCards(cards, sortSpec, history)
 			page, _ := strconv.Atoi(c.DefaultQuery("page", "1"))
 			size, _ := strconv.Atoi(c.DefaultQuery("page_size", "500"))
 			if page < 1 {
diff --git a/internal/handler/series_sort.go b/internal/handler/series_sort.go
new file mode 100644
index 0000000..be5afa6
--- /dev/null
+++ b/internal/handler/series_sort.go
@@ -0,0 +1,23 @@
+package handler
+
+import (
+	"slices"
+	"time"
+
+	"github.com/truewhile/MeBox/internal/service"
+)
+
+// sortRemoteSeriesCards keeps the DateLastContentAdded order returned by the
+// remote Emby server when LastAddedAt is not exposed in the Series DTO.
+func sortRemoteSeriesCards(cards []service.SeriesCard, spec service.MediaSortSpec, history map[string]time.Time) []service.SeriesCard {
+	if spec.Field != "updated_at" {
+		return service.SortSeriesCards(cards, spec.Field, spec.Order, history)
+	}
+
+	out := append([]service.SeriesCard(nil), cards...)
+	// RemoteSeriesCards always fetches DateLastContentAdded in descending order.
+	if spec.Order == "asc" {
+		slices.Reverse(out)
+	}
+	return service.SortSeriesCards(out, spec.Field, spec.Order, history)
+}
diff --git a/internal/handler/series_sort_test.go b/internal/handler/series_sort_test.go
new file mode 100644
index 0000000..c43aaaa
--- /dev/null
+++ b/internal/handler/series_sort_test.go
@@ -0,0 +1,21 @@
+package handler
+
+import (
+	"testing"
+
+	"github.com/truewhile/MeBox/internal/service"
+)
+
+func TestSortRemoteSeriesCardsUpdatedAtUsesRemoteOrder(t *testing.T) {
+	cards := []service.SeriesCard{{Key: "newest"}, {Key: "middle"}, {Key: "oldest"}}
+
+	desc := sortRemoteSeriesCards(cards, service.MediaSortSpec{Field: "updated_at", Order: "desc"}, nil)
+	if desc[0].Key != "newest" || desc[1].Key != "middle" || desc[2].Key != "oldest" {
+		t.Fatalf("descending order = %q, %q, %q", desc[0].Key, desc[1].Key, desc[2].Key)
+	}
+
+	asc := sortRemoteSeriesCards(cards, service.MediaSortSpec{Field: "updated_at", Order: "asc"}, nil)
+	if asc[0].Key != "oldest" || asc[1].Key != "middle" || asc[2].Key != "newest" {
+		t.Fatalf("ascending order = %q, %q, %q", asc[0].Key, asc[1].Key, asc[2].Key)
+	}
+}
diff --git a/internal/service/media_sort.go b/internal/service/media_sort.go
index 6a10d27..7811adb 100644
--- a/internal/service/media_sort.go
+++ b/internal/service/media_sort.go
@@ -70,7 +70,9 @@ func SortSeriesCards(cards []SeriesCard, field, order string, history map[string
 	}
 	sort.SliceStable(out, func(i, j int) bool {
 		cmp := compareSeriesByField(out[i], out[j], spec, history)
-		if cmp == 0 {
+		// updated_at 表示最后一集添加日期。远程卡片可能没有该字段，此时
+		// 保持调用方给定的顺序，不要用 ID 再次打乱。
+		if cmp == 0 && spec.Field != "updated_at" {
 			cmp = compareID(out[i].Key, out[j].Key)
 		}
 		return cmp < 0
@@ -173,7 +175,7 @@ func seriesUpdatedTime(card SeriesCard) (time.Time, bool) {
 	if card.LastAddedAt != nil && !card.LastAddedAt.IsZero() {
 		return *card.LastAddedAt, true
 	}
-	return mediaUpdatedTime(card.Rep)
+	return time.Time{}, false
 }
 
 func seriesLastPlayed(card SeriesCard, history map[string]time.Time) (time.Time, bool) {
diff --git a/internal/service/media_sort_test.go b/internal/service/media_sort_test.go
index 9cafa49..f45f51e 100644
--- a/internal/service/media_sort_test.go
+++ b/internal/service/media_sort_test.go
@@ -2,6 +2,7 @@ package service
 
 import (
 	"testing"
+	"time"
 
 	"github.com/truewhile/MeBox/internal/model"
 )
@@ -40,3 +41,45 @@ func TestSortSeriesCardsTitleAsc(t *testing.T) {
 		t.Fatalf("series order = %q, %q", got[0].Key, got[1].Key)
 	}
 }
+
+func TestSortSeriesCardsUpdatedAtDoesNotFallbackToMediaDate(t *testing.T) {
+	olderMediaDate := time.Date(2023, time.January, 1, 0, 0, 0, 0, time.UTC)
+	newerMediaDate := time.Date(2025, time.January, 1, 0, 0, 0, 0, time.UTC)
+	cards := []SeriesCard{
+		{
+			Key: "remote-first",
+			Rep: model.Media{Base: model.Base{
+				ID:        "remote-first",
+				CreatedAt: olderMediaDate,
+				UpdatedAt: olderMediaDate,
+			}},
+		},
+		{
+			Key: "remote-second",
+			Rep: model.Media{Base: model.Base{
+				ID:        "remote-second",
+				CreatedAt: newerMediaDate,
+				UpdatedAt: newerMediaDate,
+			}},
+		},
+	}
+
+	got := SortSeriesCards(cards, "updated_at", "desc", nil)
+	if got[0].Key != "remote-first" || got[1].Key != "remote-second" {
+		t.Fatalf("series order = %q, %q, want remote-provided order", got[0].Key, got[1].Key)
+	}
+}
+
+func TestSortSeriesCardsUpdatedAtSortsKnownLastEpisodeDates(t *testing.T) {
+	older := time.Date(2024, time.January, 1, 0, 0, 0, 0, time.UTC)
+	newer := time.Date(2025, time.January, 1, 0, 0, 0, 0, time.UTC)
+	cards := []SeriesCard{
+		{Key: "older", LastAddedAt: &older},
+		{Key: "newer", LastAddedAt: &newer},
+	}
+
+	got := SortSeriesCards(cards, "updated_at", "desc", nil)
+	if got[0].Key != "newer" || got[1].Key != "older" {
+		t.Fatalf("series order = %q, %q", got[0].Key, got[1].Key)
+	}
+}
diff --git a/web/src/utils/groupSeries.ts b/web/src/utils/groupSeries.ts
index 5d8a749..0711312 100644
--- a/web/src/utils/groupSeries.ts
+++ b/web/src/utils/groupSeries.ts
@@ -460,7 +460,7 @@ export function groupSeries(items: Media[] = []): SeriesCard[] {
             ? compactSeriesKey(externalKey)
             : getSeriesKey(m)
 
-    const mAddedAt = m.created_at || m.updated_at || ''
+    const mAddedAt = m.updated_at || m.created_at || ''
     const g = groups.get(key)
     if (!g) {
       groups.set(key, { key, rep: m, linkMedia: m, count: 1, last_added_at: mAddedAt })
diff --git a/web/src/utils/mediaSort.ts b/web/src/utils/mediaSort.ts
index cb3b43e..9ea513a 100644
--- a/web/src/utils/mediaSort.ts
+++ b/web/src/utils/mediaSort.ts
@@ -114,7 +114,7 @@ export function sortMediaList(
       case 'created_at':
         return compareDates(a.created_at, b.created_at, order) || compareStrings(a.title, b.title, 'asc')
       case 'updated_at':
-        return compareDates(a.created_at || a.updated_at, b.created_at || b.updated_at, order) || compareStrings(a.title, b.title, 'asc')
+        return compareDates(a.updated_at || a.created_at, b.updated_at || b.created_at, order) || compareStrings(a.title, b.title, 'asc')
       case 'rating':
       case 'imdb_rating': {
         const cmp = compareNumbers(a.rating || 0, b.rating || 0, order)