1. Download the corresponding mobile phone system in Xiaomi official website, put the system on the SD card of the mobile phone, and then open the settings.
2. Click on "My Device".
3. Click "MIUI Edition".
4. Click "three vertical points in the upper right corner".
5. Click "Manually select the installation package".
6. Find the ROM you downloaded and confirm it (the ROM downloaded by your browser is in the "Download" file, and the one downloaded by other browsers is in its corresponding download path).