diff --git a/AssetStudio/BuildType.cs b/AssetStudio/BuildType.cs
deleted file mode 100644
index acee230..0000000
--- a/AssetStudio/BuildType.cs
+++ /dev/null
@@ -1,20 +0,0 @@
-using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Text;
-
-namespace AssetStudio
-{
-    public class BuildType
-    {
-        private string buildType;
-
-        public BuildType(string type)
-        {
-            buildType = type;
-        }
-
-        public bool IsAlpha => buildType == "a";
-        public bool IsPatch => buildType == "p";
-    }
-}
diff --git a/AssetStudio/Classes/Mesh.cs b/AssetStudio/Classes/Mesh.cs
index 5251f7d..feccf7e 100644
--- a/AssetStudio/Classes/Mesh.cs
+++ b/AssetStudio/Classes/Mesh.cs
@@ -546,7 +546,7 @@ namespace AssetStudio
 
                 //Unity fixed it in 2017.3.1p1 and later versions
                 if (version >= (2017, 4) //2017.4
-                    || version == (2017, 3, 1) && buildType.IsPatch //fixed after 2017.3.1px
+                    || version == (2017, 3, 1) && version.IsPatch //fixed after 2017.3.1px
                     || version == (2017, 3) && m_MeshCompression == 0)//2017.3.xfx with no compression
                 {
                     var m_IndexFormat = reader.ReadInt32();
diff --git a/AssetStudio/Classes/Object.cs b/AssetStudio/Classes/Object.cs
index 664d3f7..6da762e 100644
--- a/AssetStudio/Classes/Object.cs
+++ b/AssetStudio/Classes/Object.cs
@@ -14,7 +14,6 @@ namespace AssetStudio
         public long m_PathID;
         [JsonIgnore]
         public UnityVersion version;
-        protected BuildType buildType;
         [JsonIgnore]
         public BuildTarget platform;
         [JsonConverter(typeof(JsonStringEnumConverter))]
@@ -48,7 +47,6 @@ namespace AssetStudio
             type = reader.type;
             m_PathID = reader.m_PathID;
             version = reader.version;
-            buildType = reader.buildType;
             platform = reader.platform;
             serializedType = reader.serializedType;
             classID = reader.classID;
diff --git a/AssetStudio/Classes/Sprite.cs b/AssetStudio/Classes/Sprite.cs
index 2ca4846..0c4be9c 100644
--- a/AssetStudio/Classes/Sprite.cs
+++ b/AssetStudio/Classes/Sprite.cs
@@ -214,7 +214,7 @@ namespace AssetStudio
 
             m_PixelsToUnits = reader.ReadSingle();
             if (version >= (5, 4, 2)
-                || version == (5, 4, 1) && buildType.IsPatch && version.Build >= 3) //5.4.1p3 and up
+                || version == (5, 4, 1) && version.IsPatch && version.Build >= 3) //5.4.1p3 and up
             {
                 m_Pivot = reader.ReadVector2();
             }
diff --git a/AssetStudio/ObjectReader.cs b/AssetStudio/ObjectReader.cs
index 309678e..6f2493f 100644
--- a/AssetStudio/ObjectReader.cs
+++ b/AssetStudio/ObjectReader.cs
@@ -15,7 +15,6 @@ namespace AssetStudio
         public SerializedFileFormatVersion m_Version;
 
         public UnityVersion version => assetsFile.version;
-        public BuildType buildType => assetsFile.buildType;
 
         public ObjectReader(EndianBinaryReader reader, SerializedFile assetsFile, ObjectInfo objectInfo) : base(reader.BaseStream, reader.Endian)
         {
diff --git a/AssetStudio/SerializedFile.cs b/AssetStudio/SerializedFile.cs
index e1b26c6..e10c38b 100644
--- a/AssetStudio/SerializedFile.cs
+++ b/AssetStudio/SerializedFile.cs
@@ -14,7 +14,6 @@ namespace AssetStudio
         public string originalPath;
         public string fileName;
         public UnityVersion version = new UnityVersion();
-        public BuildType buildType;
         public List<Object> Objects;
         public Dictionary<long, Object> ObjectsDic;
 
@@ -222,7 +221,6 @@ namespace AssetStudio
             if (unityVer != null && !unityVer.IsStripped)
             {
                 unityVersion = unityVer.FullVersion;
-                buildType = new BuildType(unityVer.BuildType);
                 version = unityVer;
             }
         }
diff --git a/AssetStudio/UnityVersion.cs b/AssetStudio/UnityVersion.cs
index 5a957d6..6c2ac0d 100644
--- a/AssetStudio/UnityVersion.cs
+++ b/AssetStudio/UnityVersion.cs
@@ -4,6 +4,16 @@ using System.Text.RegularExpressions;
 
 namespace AssetStudio
 {
+    public static class BuildTypes
+    {
+        public static readonly string
+            Alpha = "a",
+            Beta = "b",
+            Final = "f",
+            Patch = "p",
+            Tuanjie = "t";
+    }
+
     public class UnityVersion : IComparable
     {
         public int Major { get; }
@@ -14,6 +24,10 @@ namespace AssetStudio
         public string FullVersion { get; }
 
         public bool IsStripped => this == (0, 0, 0);
+        public bool IsAlpha => BuildType == BuildTypes.Alpha;
+        public bool IsBeta => BuildType == BuildTypes.Beta;
+        public bool IsPatch => BuildType == BuildTypes.Patch;
+        public bool IsTuanjie => BuildType == BuildTypes.Tuanjie;
 
         public UnityVersion(string version)
         {
@@ -47,7 +61,7 @@ namespace AssetStudio
             if (!IsStripped)
             {
                 Build = 1;
-                BuildType = "f";
+                BuildType = BuildTypes.Final;
                 FullVersion += $"{BuildType}{Build}";
             }
         }