1. The internal status of the phone is out of the question. In general, re-opening "USB debugging" can solve this problem, but sometimes you need to restart your phone or PC.
2.USB Insufficient power supply. If this is the case, then you need to replace the USB cable or USB jack.
3. No corresponding driver is installed. This problem is generally only available for Windows users, and installing drivers can solve the problem. If you are a Linux or Mac OS x user, you do not need to install drivers.
4. Other program interference. As far as I'm concerned, it's often the case that the "pea clip" runs, causing Eclipse to not recognize the phone. Kill it.
5.ADB and other versions are too low. Upgrading Android's range of development tools and SDKs will solve the problem.
Summary of scenarios where Android development tools do not recognize Android phones