先看效果

实现方案

1：创建几个用于测试的Cube

2：创建一个脚本

3:编写脚本内容

主要是这部分的逻辑

附上完整代码

using System.Collections;
using System.Collections.Generic;
using UnityEditor;
using UnityEngine;

public class Tool
{
    [MenuItem("TOOL/ReplaceMaterial")]
    public static void Open()
    {
        var window = EditorWindow.GetWindow(typeof(ReplaceMA));
        window.title = "材质球替换工具";
    }
}
public class ReplaceMA : EditorWindow
{
    private GameObject _GameObject;
    private Material _Material;

    private void OnGUI()
    {
        if (!Application.isPlaying)
        {
            GUILayout.Label("拖入一个你想替换材质球的游戏物体");
            _GameObject = (GameObject)EditorGUILayout.ObjectField(_GameObject, typeof(GameObject), true);
            GUILayout.Label("拖入一个你想替换的材质球");
            _Material = (Material)EditorGUILayout.ObjectField(_Material, typeof(Material), true);

            if (GUILayout.Button("点击替换"))
            {
                if (_GameObject == null || _Material == null)
                {
                    Debug.LogError("你要替换材质的游戏物体或者材质球为空");
                    return;
                }
                var RenderList = new List<Renderer>();
                RenderList.Add(_GameObject.gameObject.GetComponent<Renderer>());
                RenderList.AddRange(_GameObject.GetComponentsInChildren<Renderer>());
                Undo.RecordObjects(RenderList.ToArray(), "Replace");//这句话非常重要，不然得气死个人！！！
                foreach (var item in RenderList)
                {
                    var materials = item.sharedMaterials;
                    for (int i = 0; i < materials.Length; i++)
                    {
                        materials[i] = _Material;
                    }
                    item.sharedMaterials = materials;
                }
            }
        }
    }
}

4，然后就完成啦，同样你也可以按照我的思路再扩展扩展，可以替换你自己想要的内容