Abstract: Aiming at the multiple fieldbus technology is widely used in the electronic equipment contained in airborne, onboard, the design of a FPGA-based multi-protocol isolated bus signal simulator, including RS232, RS422, RS485, CAN bus and ARINC-429 five types to achieve signal simulation for electronic device applications of fieldbus technology. By compared the collected measured module output bus parameters with send data, detection of airborne or missile borne electronic equipment is working properly. The signal simulator can be based on user's configuration, and then generate multiple electrically isolated from each other, multi-protocol, different baud rate digital bus signal, with a high degree of stability.