How to autorun apk on android by plugging usb?
It's not possible to install packages automatically, and there's no feature like AutoRun. AutoRun was a huge security problem on Windows systems, so it seems unlikely that a similar feature will be added to Android. You just have to put the APK file on the USB stick and install it by opening it with the package installer.

It would be possible to make an app that listens for USB connection events, scans for APK files, and asks the package installer to install any APK files it finds, but the app would have to be already installed on the phone, and the user would still have to click to accept the installation of the new apps.