As the common method using JTAG to update the programs of DSP and FPGA is limited by the environment and equipment, there is a need for remote updating. This paper proposes a method based on RS-422 serial communication and HDLC protocol. Comparing with other remote updating methods, it is fast, stable and easy to be implemented. Apart from this, we design a system to verify the method. At last, we do an experiment to show the full process.