The commonly used JTAG method to update the FPGA program is limited by factors such as the structure and installation location of the device, lack of flexibility, and has the disadvantages of complicated disassembly and assembly, low upgrade efficiency and poor maintenance. Aiming at this situation, the paper designs a way to realize FPGA update through the serial port. This method sends the required update program data to the FPGA through the PC. According to the data transmission logic and control logic implemented in the FPGA, combined with the dedicated IP circuit, The update program data is stored in the FPGA system to implement the update of the configuration file. After reloading the FPGA system, the correctness and feasibility of the design were verified. The software update is implemented through the serial port of the device, which does not increase the additional hardware overhead, effectively solves the problem of inconvenient assembly and cumbersome operation of the device, improves the field work efficiency, and saves labor costs.