diff --git a/Build_God_Api/Build_God_Api/Services/CharacterService.cs b/Build_God_Api/Build_God_Api/Services/CharacterService.cs
index 01294d3..d24f66c 100644
--- a/Build_God_Api/Build_God_Api/Services/CharacterService.cs
+++ b/Build_God_Api/Build_God_Api/Services/CharacterService.cs
@@ -104,8 +104,14 @@ namespace Build_God_Api.Services
                 return true;
             }
 
+            // 存储的突破率可能为 0（新建角色未初始化）或历史数据低于当前境界基础概率；
+            // 实际判定应至少使用当前境界 BaseBreakthroughRate，失败累加也要在“不低于基础”之上再加 FailIncrement。
+            var rateForRoll = character.BreakthroughRate < currentLevel!.BaseBreakthroughRate
+                ? currentLevel.BaseBreakthroughRate
+                : character.BreakthroughRate;
+
             decimal randomValue = GenerateSecureRandomDecimal(0, 100, 1);
-            bool isSuccess = randomValue < character.BreakthroughRate;
+            bool isSuccess = randomValue < rateForRoll;
 
             if (isSuccess)
             {
@@ -116,7 +122,9 @@ namespace Build_God_Api.Services
             }
             else
             {
-                character.BreakthroughRate += currentLevel!.FailIncrement;
+                if (character.BreakthroughRate < currentLevel.BaseBreakthroughRate)
+                    character.BreakthroughRate = currentLevel.BaseBreakthroughRate;
+                character.BreakthroughRate += currentLevel.FailIncrement;
                 if (character.BreakthroughRate > 100)
                 {
                     character.BreakthroughRate = 100;
@@ -176,13 +184,12 @@ namespace Build_God_Api.Services
         /// <returns>随机数</returns>
         private decimal GenerateSecureRandomDecimal(decimal min, decimal max, int decimalPlaces)
         {
-            byte[] randomBytes = new byte[4];
+            Span<byte> randomBytes = stackalloc byte[4];
             _rng.GetBytes(randomBytes);
-            int randomInt = BitConverter.ToInt32(randomBytes, 0);
-
-            decimal randomDecimal = (decimal)Math.Abs(randomInt) / int.MaxValue;
-            decimal result = min + (randomDecimal * (max - min));
-
+            var u = BitConverter.ToUInt32(randomBytes);
+            // [0, uint.MaxValue] -> [0m, 1m]，避免 int.MinValue 时 Math.Abs 溢出
+            decimal randomUnit = (decimal)u / uint.MaxValue;
+            decimal result = min + randomUnit * (max - min);
             return Math.Round(result, decimalPlaces);
         }
 
@@ -338,17 +345,20 @@ namespace Build_God_Api.Services
                 throw new Exception("每个账号最多只能创建3个角色");
             }
 
+            const int startLevelId = 10;
+            var startLevel = await db.Queryable<Level>().FirstAsync(x => x.LevelId == startLevelId);
+
             Character newOne = new()
             {
                 Name = character.Name,
                 AccountId = currentUserService.UserId,
                 CurrentExp = 0,
-                LevelId = 10,
+                LevelId = startLevelId,
                 Money = 0,
                 CurrentHP = 100,
                 ProfessionId = character.ProfessionId,
                 SpiritFieldId = 0,
-                BreakthroughRate = 0,
+                BreakthroughRate = startLevel?.BaseBreakthroughRate ?? 0,
                 LastLogin = DateTime.Now
             };