At present, industrial equipment often needs microprocessor such as digital signal processor (DSP) to enhance automation capability. However, because of the problems of equipment space and update efficiency, the emulator could not be used to maintain and update programs. In order to solve the above problems, a dual core system based on SCI serial communication is designed to realize DSP online programming in this paper. In this system, the DSP chip is connected with the host computer and the auxiliary chip STM32 through the SCI serial port respectively. The DSP receives instructions and user program data through the SCI serial port and completes the online updating of the program. The experimental results show that this method couldeffectively improve the maintainability of the equipment. At the same time, because there is no need to repeatedly insert the JTAG port on the PCB one by one, the efficiency of updating the equipment software could be greatly improved.