Hehe, you didn't find such a simple question? But I think the landlord is also a beginner of single chip microcomputer, so am I. If you don't mind, you can add me QQ1101289214. Don't talk nonsense Solution: Right-click the "My Computer" icon on the desktop, and then click "Device Manager" to open the following window. Look at the selected icon, click on it, and see what the COM port is at the back. Mine is COM3. Of course, if you change the USB port, COM will also change. Then when you download the software of single chip microcomputer and choose COM port, you can choose the corresponding one.