diff --git a/Assets/Tests/EditMode/Core/WeightedPickTests.cs b/Assets/Tests/EditMode/Core/WeightedPickTests.cs
new file mode 100644
index 00000000..d2f99280
--- /dev/null
+++ b/Assets/Tests/EditMode/Core/WeightedPickTests.cs
@@ -0,0 +1,98 @@
+using System.Collections.Generic;
+using NUnit.Framework;
+using BaseGames.Core;
+
+namespace BaseGames.Tests.EditMode.Core
+{
+    /// <summary>
+    /// WeightedPick 加权随机取索引的共享原语测试。
+    /// 该原语被敌人选招 / Boss 选招 / 战利品掉落共用，故对"绝不选中零权重项"等
+    /// 确定性性质做强断言（多次采样），避免任一消费端出现选到不合格项的缺陷。
+    /// </summary>
+    public class WeightedPickTests
+    {
+        static List<float> W(params float[] w) => new List<float>(w);
+
+        [Test]
+        public void Null_ReturnsMinusOne()
+        {
+            Assert.AreEqual(-1, WeightedPick.Index(null));
+        }
+
+        [Test]
+        public void Empty_ReturnsMinusOne()
+        {
+            Assert.AreEqual(-1, WeightedPick.Index(W()));
+        }
+
+        [Test]
+        public void AllZero_ReturnsMinusOne()
+        {
+            Assert.AreEqual(-1, WeightedPick.Index(W(0f, 0f, 0f)));
+        }
+
+        [Test]
+        public void AllNegative_ReturnsMinusOne()
+        {
+            // 负权重按 0 处理（非法输入不应造成负总和/错误索引）
+            Assert.AreEqual(-1, WeightedPick.Index(W(-1f, -5f)));
+        }
+
+        [Test]
+        public void SinglePositive_AlwaysThatIndex()
+        {
+            var w = W(0f, 3f, 0f);
+            for (int i = 0; i < 50; i++)
+                Assert.AreEqual(1, WeightedPick.Index(w));
+        }
+
+        [Test]
+        public void NeverPicksZeroWeight()
+        {
+            // 索引 0/2 权重为 0，无论抽多少次都不该被选中
+            var w = W(0f, 1f, 0f, 2f);
+            for (int i = 0; i < 200; i++)
+            {
+                int idx = WeightedPick.Index(w);
+                Assert.IsTrue(idx == 1 || idx == 3, $"选中了零权重索引 {idx}");
+            }
+        }
+
+        [Test]
+        public void NeverPicksNegativeWeight()
+        {
+            var w = W(-10f, 1f);
+            for (int i = 0; i < 200; i++)
+                Assert.AreEqual(1, WeightedPick.Index(w));
+        }
+
+        [Test]
+        public void AllPositive_EveryIndexReachable()
+        {
+            // 等权重下，足够多次采样应覆盖所有索引（验证不会恒定只返回首个/末个）
+            var w = W(1f, 1f, 1f);
+            var seen = new HashSet<int>();
+            for (int i = 0; i < 500; i++) seen.Add(WeightedPick.Index(w));
+            CollectionAssert.AreEquivalent(new[] { 0, 1, 2 }, seen);
+        }
+
+        [Test]
+        public void HeavyWeight_DominatesDistribution()
+        {
+            // 权重 99:1 时，重权重索引应占绝大多数（宽松阈值，避免随机性造成偶发失败）
+            var w = W(99f, 1f);
+            int heavy = 0;
+            const int N = 1000;
+            for (int i = 0; i < N; i++) if (WeightedPick.Index(w) == 0) heavy++;
+            Assert.Greater(heavy, N * 0.9f, $"重权重仅被选中 {heavy}/{N} 次，分布不符合权重");
+        }
+
+        [Test]
+        public void WorksWithArray()
+        {
+            // IReadOnlyList 契约：数组同样可用（消费端可复用缓存数组，免 GC）
+            float[] w = { 0f, 5f };
+            Assert.AreEqual(1, WeightedPick.Index(w));
+        }
+    }
+}
diff --git a/Assets/_Game/Scripts/Core/Utils/WeightedPick.cs b/Assets/_Game/Scripts/Core/Utils/WeightedPick.cs
new file mode 100644
index 00000000..21affd6b
--- /dev/null
+++ b/Assets/_Game/Scripts/Core/Utils/WeightedPick.cs
@@ -0,0 +1,51 @@
+using System.Collections.Generic;
+using UnityEngine;
+
+namespace BaseGames.Core
+{
+    /// <summary>
+    /// 加权随机取索引的共享原语（纯逻辑、无状态、可单测）。
+    ///
+    /// 项目中"按权重随机选一个"的场景（敌人选招 / Boss 选招 / 战利品掉落）此前各写了一份
+    /// 累加-掷点-回退的循环，语义相同却各自维护。统一到本处，消除平行实现。
+    ///
+    /// 调用方职责：把候选的**有效权重**填入一个列表/数组（不合格候选填 0），
+    /// 本原语只负责"按权重挑一个索引"，不关心候选是什么、为何不合格。
+    /// 列表可由调用方缓存复用 → 选取过程零 GC 分配。
+    /// </summary>
+    public static class WeightedPick
+    {
+        /// <summary>
+        /// 按 <paramref name="weights"/> 加权随机返回一个索引。
+        /// 权重 ≤ 0 的项永不被选中（负权重按 0 处理）；无任何正权重时返回 -1。
+        /// </summary>
+        public static int Index(IReadOnlyList<float> weights)
+        {
+            if (weights == null) return -1;
+
+            int count = weights.Count;
+            float total = 0f;
+            for (int i = 0; i < count; i++)
+            {
+                float w = weights[i];
+                if (w > 0f) total += w;
+            }
+            if (total <= 0f) return -1;
+
+            float roll = Random.value * total;
+            float accum = 0f;
+            for (int i = 0; i < count; i++)
+            {
+                float w = weights[i];
+                if (w <= 0f) continue;
+                accum += w;
+                if (roll <= accum) return i;
+            }
+
+            // 浮点累加误差兜底：返回最后一个正权重项（绝不返回零权重项）
+            for (int i = count - 1; i >= 0; i--)
+                if (weights[i] > 0f) return i;
+            return -1;
+        }
+    }
+}