To install the APK file downloaded from QQ on your mobile phone, you can follow the following steps: Open QQ on your mobile phone and find the APK file on the page. Click to open the downloaded APK file, and click "Install" in the pop-up page. Click Allow this installation at the prompt to start installing the application. In addition, you can use third-party software to open and install APK files. The following are some recommended software: MT Manager: download and install MT Manager, receive APK file after opening, select other applications to open, and select MT Manager to open. Then MT Manager will automatically jump to and find the newly received file, press and hold the file to select Rename, and delete ".1" before normal installation. Other third-party software: such as wx assistant, Ding Xiaotiao, lion installation, R installation components, etc. These softwares usually have the function of identifying and installing APK files. Please note that the above steps may be different depending on the phone model and system version. It is recommended to know your mobile phone model and system version before operation to ensure the correct installation of APK files.