diff --git a/src/features/lucky-gift/configModel.js b/src/features/lucky-gift/configModel.js
index 3f0b9a1..d64cba8 100644
--- a/src/features/lucky-gift/configModel.js
+++ b/src/features/lucky-gift/configModel.js
@@ -130,12 +130,16 @@ export function addTierToStage(stages, stageKey) {
         if (stage.stage !== stageKey) {
             return stage;
         }
-        const index = stage.tiers.length + 1;
+        const nextMultiplier = nextSuggestedTierMultiplier(stage.tiers);
         return {
             ...stage,
             tiers: [
                 ...stage.tiers,
-                tier(`${stage.stage}_${index}x`, "", "", { broadcastLevel: "none", rewardSource: "base_rtp" }),
+                tier(tierIDFromMultiplier(stage.stage, nextMultiplier), nextMultiplier, "", {
+                    broadcastLevel: "none",
+                    highWaterOnly: nextMultiplier >= 5,
+                    rewardSource: "base_rtp",
+                }),
             ],
         };
     });
@@ -231,6 +235,28 @@ function defaultStages() {
     return stageOptions.map(([stage]) => ({ stage, tiers: defaultStageTiers[stage].map((item) => ({ ...item })) }));
 }
 
+function nextSuggestedTierMultiplier(tiers) {
+    const usedMultipliers = (tiers || [])
+        .map((item) => decimal(item.multiplier))
+        .filter((value) => Number.isFinite(value) && value > 0);
+    if (usedMultipliers.length === 0) {
+        return 1;
+    }
+    const maxMultiplier = Math.max(...usedMultipliers);
+    if (maxMultiplier >= 5) {
+        return maxMultiplier * 2;
+    }
+    if (maxMultiplier >= 2) {
+        return 5;
+    }
+    return maxMultiplier + 1;
+}
+
+function tierIDFromMultiplier(stage, multiplier) {
+    const multiplierText = String(multiplier).replace(".", "_");
+    return `${stage}_${multiplierText}x`;
+}
+
 function normalizeStages(stages) {
     // server 返回缺阶段时仍用默认三阶段补齐表单，保证运营看到的是完整发布形态；
     // 保存时 schema 会再次校验概率合计和 0x 档，不让半成品配置进入发布请求。
diff --git a/src/features/lucky-gift/configModel.test.js b/src/features/lucky-gift/configModel.test.js
index b509263..c0db68c 100644
--- a/src/features/lucky-gift/configModel.test.js
+++ b/src/features/lucky-gift/configModel.test.js
@@ -56,7 +56,13 @@ describe("lucky gift config payload", () => {
         const advanced = nextStages.find((stage) => stage.stage === "advanced");
 
         expect(advanced.tiers).toHaveLength(5);
-        expect(advanced.tiers[4]).toMatchObject({ broadcastLevel: "none", rewardSource: "base_rtp" });
+        expect(advanced.tiers[4]).toMatchObject({
+            broadcastLevel: "none",
+            highWaterOnly: true,
+            multiplier: 10,
+            rewardSource: "base_rtp",
+            tierId: "advanced_10x",
+        });
     });
 
     test("corrects a stage probability to requested RTP without zeroing enabled tiers", () => {
diff --git a/src/features/lucky-gift/schema.test.ts b/src/features/lucky-gift/schema.test.ts
index 005a6ea..28bca55 100644
--- a/src/features/lucky-gift/schema.test.ts
+++ b/src/features/lucky-gift/schema.test.ts
@@ -18,4 +18,28 @@ describe("lucky gift config schema", () => {
             expect(result.error.issues.map((issue) => issue.message)).toContain("启用奖档概率合计必须等于 100%");
         }
     });
+
+    test("rejects duplicated tier id inside the same stage before submit", () => {
+        const form = emptyLuckyGiftForm();
+        const advanced = form.stages.find((stage: { stage: string }) => stage.stage === "advanced");
+        if (!advanced) {
+            throw new Error("advanced stage missing");
+        }
+        advanced.tiers = [
+            ...advanced.tiers,
+            {
+                ...advanced.tiers[advanced.tiers.length - 1],
+                multiplier: 10,
+                probabilityPercent: 0,
+                tierId: "advanced_5x",
+            },
+        ];
+
+        const result = luckyGiftConfigFormSchema.safeParse(form);
+
+        expect(result.success).toBe(false);
+        if (!result.success) {
+            expect(result.error.issues.map((issue) => issue.message)).toContain("同一阶段内奖档 ID 不能重复");
+        }
+    });
 });
diff --git a/src/features/lucky-gift/schema.ts b/src/features/lucky-gift/schema.ts
index 34f6aeb..de949d0 100644
--- a/src/features/lucky-gift/schema.ts
+++ b/src/features/lucky-gift/schema.ts
@@ -93,6 +93,18 @@ export const luckyGiftConfigFormSchema = z
                     path: ["stages", stageIndex, "tiers"],
                 });
             }
+            const tierIDSet = new Set<string>();
+            stage.tiers.forEach((tier, tierIndex) => {
+                const tierID = String(tier.tierId || "").trim();
+                if (tierIDSet.has(tierID)) {
+                    context.addIssue({
+                        code: "custom",
+                        message: "同一阶段内奖档 ID 不能重复",
+                        path: ["stages", stageIndex, "tiers", tierIndex, "tierId"],
+                    });
+                }
+                tierIDSet.add(tierID);
+            });
             const expectedRTPPPM = stage.tiers.reduce((sum, tier) => {
                 if (!tier.enabled || tier.rewardSource !== "base_rtp") {
                     return sum;