According the controller area network (CAN) used in the existing distributed locomotive fault detecting and recording system not suitable for vehicles bus, the scheme using the multifunction vehicle bus (MVB) was proposed. The key design concepts of system structure and operating principle alteration were described in detail, and the multi-function interface MVB adapter based on SOPC (system on a programmable chip) technology was designed. Hardware and software realization of the design was given, and its correctness and feasibility were verified ultimately by the network test in the lab. The improved network has farther transmission distance, higher rates, better reliability and real-time performance.