这是因为你的checkbutton控件将第一列撑大了,可以用columnspan option调整
from tkinter import *
root = Tk()
root.geometry('600x600')
header = Frame()
mid = Frame()
footer = Frame()
font = (None, 15)
text = Label(header, text = 'name:', font = font)
text.grid(row = 0, column = 1, sticky = W)
enter = Text(header, height = 1, font = font)
enter.grid(row = 0, column = 2)
inti = IntVar()
choose = Checkbutton(header, text = 'I want to set a password', variable = inti, font = font)
choose.grid(row = 2, column = 1, columnspan = 2,sticky = 'w',pady = 20,padx = 30)
header.pack()
mainloop()