编辑器代码以及kuang：

UnityEditor.AssetDataBase.LoadAseetAtPath<GameObject>("");

参数是相对路径，Assets文件夹下的相对路径，需要后缀名.prefab。

1、通过Resources加载
 GameObject obj = GameObject.Instantiate(Resources.Load("myPrefab") as GameObject);

2、在菜单栏添加菜单，程序集打包
    using UnityEditor;
    [MenuItem("Tools/打包")]
    public static void Build()
    {
        BuildPipeline.BuildAssetBundles(Application.streamingAssetsPath, BuildAssetBundleOptions.ChunkBasedCompression, EditorUserBuildSettings.activeBuildTarget);
        AssetDatabase.Refresh(); /*编辑器刷新*/
    }
3、通过AssetBundle加载
    AssetBundle assetBundle = AssetBundle.LoadFromFile(Application.streamingAssetsPath + "/myPreFabs");
    GameObject gameObject = GameObject.Instantiate(assetBundle.LoadAsset<GameObject>("myPreFab1"));
    
4、AssetDatabase.LoadAssetAtPath方式加载        
GameObject gameObject = GameObject.Instantiate(UnityEditor.AssetDatabase.LoadAssetAtPath<GameObject>("Assets/GameData/Prefabs/myPreFab1.prefab"));