系统环境变量
winreg.HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Environment'
用户环境变量
HKEY_CURRENT_USER\Environment
path_key = winreg.OpenKey(winreg.HKEY_LOCAL_MACHINE, r'SYSTEM\CurrentControlSet\Control\Session Manager\Environment', 0, winreg.KEY_ALL_ACCESS)
path_value = winreg.QueryValueEx(path_key, 'Path')
winreg.SetValueEx(path_key, "Path", 0, winreg.REG_EXPAND_SZ, '新的环境变量')
# 刷新注册表 更新环境变量
HWND_BROADCAST = 0xFFFF
WM_SETTINGCHANGE = 0x1A
SMTO_ABORTIFHUNG = 0x0002
result = ctypes.c_long()
SendMessageTimeoutW = ctypes.windll.user32.SendMessageTimeoutW
SendMessageTimeoutW(HWND_BROADCAST, WM_SETTINGCHANGE, 0, u'Environment', SMTO_ABORTIFHUNG, 5000, ctypes.byref(result))