In this case, if your current Xiaomi mobile phone belongs to the new version and intends to downgrade to the old version, it will not be easy for you to operate it yourself at this time, which means that the system can be restored to the original state after the upgrade, but the performance of this mobile phone and the compatibility of the mobile phone are much worse, and some system errors are prone to occur. If you plan to brush back the old version, download the system version corresponding to the mobile phone model in Xiaomi official website at this time. After finding the old version, download an installation package and then download it to your mobile phone. When the mobile phone is turned on, press the power-on key and the volume plus key at the same time again to enter, then find the mobile phone installation package in the second option below, click OK to decompress, and then install. After restarting, this will be your newly installed version.