依照樓主要寫的遊戲，我用自己想的邏輯加上一些樓主寫好的函式，做出來的功能應該是差不多的東西，有些寫法可以再優化不過已經比樓主貼上來的程式碼少了三分之一左右，貼上來給樓主參考，寫程式能簡化的儘量簡化，能用一個陣列解決的，就不要用到第二個陣列...

import os,random

def drawBoard(board):
	print("┌──┬──┬──┐")
	print("│  "+board[0]+" │  "+board[1]+" │  "+board[2]+" │")
	print("├──┼──┼──┤")
	print("│  "+board[3]+" │  "+board[4]+" │  "+board[5]+" │")
	print("├──┼──┼──┤")
	print("│  "+board[6]+" │  "+board[7]+" │  "+board[8]+" │")
	print("└──┴──┴──┘")

def whoGo1st():
	a=random.randint(0,1)
	if a==0:
		print('You go 1st.')
		return 0
	else:
		print('Com go 1st.')
		return 1

def isWin(b,L):
	return (b[1]==L and b[2]==L and b[0]==L) or (b[4]==L and b[5]==L and b[3]==L) or (b[7]==L and b[8]==L and b[6]==L) or (b[0]==L and b[3]==L and b[6]==L) or (b[1]==L and b[4]==L and b[7]==L) or (b[2]==L and b[5]==L and b[8]==L) or (b[0]==L and b[4]==L and b[8]==L) or (b[2]==L and b[4]==L and b[6]==L)

def change_player():
	global c_flag
	c_flag = 1 if c_flag==0 else 0

def check_moves(arg):
	global my_arr,my_choice,c_flag,com_choice,steps
	if arg>9 or arg<1:
		return False
	elif my_arr[arg-1]=='O' or my_arr[arg-1]=='X':
		return False
	else:
		if c_flag==0:
			my_arr[arg-1]=my_choice
		else:
			my_arr[arg-1]=com_choice
		steps=steps+1
		return True

def do_move(player):
	while 1:
		print('You['+my_choice+']  Com:['+com_choice+']')
		if player==0:
			tmp_input=input('Input a number to choose the place:(1-9)')
			if tmp_input.upper()=='Q': exit()
		else:
			tmp_input=random.randint(0, 9)
		if check_moves(int(tmp_input)):
			break

def do_my_choice():
	global my_choice,com_choice
	while 1:
		my_choice=input("Do you want 'O' or 'X'?").upper()
		if my_choice=='O' or  my_choice=='X': 
			com_choice= 'X' if my_choice=='O' else 'O'
			break
		if my_choice=='Q': exit()

def cls(): os.system("cls")

def game_init():
	global my_arr,my_choice,com_choice,c_flag,steps
	my_arr=['1','2','3','4','5','6','7','8','9']
	my_choice=''
	com_choice=''
	steps=0
	c_flag=-1
def game_start():
	global c_flag,my_arr,my_choice,com_choice,steps
	game_init()
	cls()
	print('Welcome to Tic Tac Toe!!!')
	c_flag=whoGo1st()
	do_my_choice()
	while 1:
		cls()
		drawBoard(my_arr)
		if isWin(my_arr,my_choice):
			print("U WIN")
			break
		elif isWin(my_arr,com_choice):
			print("Com WIN")
			break
		elif steps==9:
			print("DRAWN GAME!")
			break
		do_move(c_flag)
		change_player()

def ask_play_again():
	return True if input("PLAY AGAIN?( Y or N )...").upper()=='Y' else False

if __name__ == '__main__':
	while 1:
		game_start()
		if ask_play_again()==False:
			print("Bye!!!")
			break

你的程式碼不完整,
所以有可能問題不是如你寫的那樣,
另外break只能跳出一個迴圈,
如果你有兩層迴圈,
break只會跳出裡面那層,
而外面那層還是會繼續進行.