The annual fee can be paid through the local Municipal Science and Technology Bureau or through the patent agency.
Through the Municipal Science and Technology Bureau, you can go directly to the local Municipal Science and Technology Bureau, provide them with your patent number and inquire about the annual fee of the patent. The staff of the Science and Technology Bureau will tell you how much the annual fee is, and you can pay it.
If it is not convenient to go to the Science and Technology Bureau, you can also find the relevant patent agency to hand it in yourself. When an agency pays an annual fee, it needs to charge a certain handling fee.