diff --git a/services/activity-service/internal/service/luckygift/config.go b/services/activity-service/internal/service/luckygift/config.go
index 0955616a..f571b7a8 100644
--- a/services/activity-service/internal/service/luckygift/config.go
+++ b/services/activity-service/internal/service/luckygift/config.go
@@ -162,6 +162,7 @@ func validateRuleStage(stage domain.RuleStage) error {
 	var weightSum int64
 	hasBaseTier := false
 	hasZeroTier := false
+	tierIDs := make(map[string]struct{}, len(stage.Tiers))
 	for _, tier := range stage.Tiers {
 		if tier.Stage != stage.Stage {
 			return xerr.New(xerr.InvalidArgument, fmt.Sprintf("tier %s stage does not match %s", tier.TierID, stage.Stage))
@@ -169,6 +170,11 @@ func validateRuleStage(stage domain.RuleStage) error {
 		if tier.TierID == "" {
 			return xerr.New(xerr.InvalidArgument, fmt.Sprintf("%s tier id is required", stage.Stage))
 		}
+		// 同阶段奖档 ID 是 lucky_gift_stage_tiers 的主键维度；发布前拦截重复值，避免运营配置错误落到数据库唯一键后变成 opaque internal error。
+		if _, exists := tierIDs[tier.TierID]; exists {
+			return xerr.New(xerr.InvalidArgument, fmt.Sprintf("%s tier id is duplicated: %s", stage.Stage, tier.TierID))
+		}
+		tierIDs[tier.TierID] = struct{}{}
 		if tier.MultiplierPPM < 0 {
 			return xerr.New(xerr.InvalidArgument, fmt.Sprintf("%s tier multiplier is invalid", tier.TierID))
 		}
diff --git a/services/activity-service/internal/service/luckygift/config_test.go b/services/activity-service/internal/service/luckygift/config_test.go
index 5328d272..e410ed7f 100644
--- a/services/activity-service/internal/service/luckygift/config_test.go
+++ b/services/activity-service/internal/service/luckygift/config_test.go
@@ -57,3 +57,16 @@ func TestValidateRuleConfigRequiresExplicitZeroTier(t *testing.T) {
 		t.Fatalf("expected stage without 0x tier to be rejected")
 	}
 }
+
+func TestValidateRuleConfigRejectsDuplicatedStageTierID(t *testing.T) {
+	config := DefaultRuleConfig("hyapp", "pool_duplicate_tier")
+	advanced := &config.Stages[2]
+	duplicate := advanced.Tiers[len(advanced.Tiers)-1]
+	duplicate.MultiplierPPM = 10_000_000
+	duplicate.BaseWeightPPM = 0
+	advanced.Tiers = append(advanced.Tiers, duplicate)
+
+	if err := validateRuleConfig(config); err == nil {
+		t.Fatalf("expected duplicate tier id inside one stage to be rejected")
+	}
+}