The development of USB communication drivers in power system fault simulation test devices is discussed. In the Windows operating system, USB device drivers are designed according to WDM (Windows Driver Model). In the WDM driver model, each hardware device has at least two drivers, one of which is called a function driver, which is usually a hardware device driver. It understands all the details of making the hardware work, is responsible for initializing the I/O operation, handles the interrupt event brought when the I/O operation is completed, and provides the user with a control method suitable for the device; Another driver provided by the operating system is called the bus driver and it is responsible for managing the connection of the hardware to the computer.