The existing bus fault injection system mostly inject faults for single bus, it cannot satisfy the dynamic and real-time simulation test requirements of the electrical fault in the multi-type bus system. In order to simulate the response of multiple buses in multiple fault modes, an electrical fault injection system for multi-type bus is built, and describe the advantages of the fault injection system in the weapon system with multiple buses. Through simultaneous fault injection test of the protocol layer of CAN and the electrical layer of RS422, the validity of the fault injection system in multi-class bus and multiple fault modes is verified.