Abstract: In view of problem that current switched reluctance drive systems are lack of friendly human machine interface to display running state of the system and set given parameters, the paper proposed a design scheme of human machine interface of switched reluctance drive system based on simplified ModBus communication protocol. It gave general structure of the switched reluctance drive system, and introduced design of serial communication circuit and communication program in the human machine interface. Debugging result shows that the human machine interface runs stably and realizes functions of friendly display and online parameters modification for the switched reluctance drive system.