pointer中的代码不需要从pointer导入数据，而是需要给予对小部件的访问权限授予Beautifier类。您可以通过多种方式来实现这一点-您可以将数据传递给Beautifier.__init__，或者传递给beautifying。或者，您可以在pointer.py中创建一个更新其自己的小部件的函数，并将其作为回调传递。
下面是后者的一个示例，将回调传递给Beautifier.__init__：

美化数据.py

class Beautifier:
    def __init__(self, beautiful_payload, callback=None):
        self.new = beautiful_payload
        self.callback = callback

    def beautifying(self):
        json_object = json.loads(self.new) 
        new_json = json.dumps(json_object, indent=4) 
        if self.callback:
            self.callback(new_json)
        return new_json

pointer.py

def update_ui(new_json):
    text_box.delete('1.0', "end")
    text_box.insert('1.0', new_json)
    payload_field.set(new_json)
...
mytest = Beautifier(get_text_box, update_ui)
new = mytest.beautifying()
...

我建议从Beautifier.__init__中删除beautiful_payload，并将其传递给beautifying，这样您就可以创建一个示例，然后多次使用它，而不必每次都创建一个新示例。

美化数据.py：

class Beautifier:
    def __init__(self, callback=None):
        self.callback = callback

    def beautifying(self, payload):
        json_object = json.loads(payload) 
        new_json = json.dumps(json_object, indent=4) 
        if self.callback:
            self.callback(new_json)
        return new_json

pointer.py

...
mytest = Beautifier(callback=update_ui)
get_text_box = text_box.get("1.0", END)
new = mytest.beautifying(get_text_box)
...

最好更新pointer.py中的小部件，这样就不需要在beautify_data.py中导入pointer.py：

美化数据.py

import json

class Beautifier:
    def beautifying(self, txt):
        try:
            json_object = json.loads(txt)
            new_json = json.dumps(json_object, indent=4) 
            return new_json
        except json.decoder.JSONDecodeError as ex:
            print(ex)

pointer.py

from tkinter import *
from tkinter import ttk
from beautify_data import Beautifier

def beautify_json():
    get_text_box = text_box.get("1.0", "end-1c")
    mytest = Beautifier()
    result = mytest.beautifying(get_text_box)
    if result:
        text_box.delete("1.0", END)
        text_box.insert(END, result)

window = Tk()

text_box = Text(window, width=68, height=29, fg="white", bg="black", insertbackground="white", font=("Helvetica", 17))
text_box.grid(row=0, column=0, sticky="nsew")

button_save_payload = ttk.Button(width=8, text="BEAUTIFY", command=beautify_json)
button_save_payload.grid(row=1, column=0, sticky="e")

window.mainloop()