Abstract: In view of the problems that single exchange module function, poor protocol conversion real-time performance and the existing substation can not meet video access when existing monitoring substation collects data by exchanging module access ring net, the paper proposes a design scheme based on FPGA multi-function switching module and design scheme of RS485 / CAN protocol conversion and video transmission in coal mine. The paper introduces software and hardware architecture of substation design in detail and using the ping-pong storage way to solve the mismatch problem. The FPGA implements RS485 interface rate and Ethernet protocol transformation of key processing technology, video access key technology. Through existing upgrade project trial results show that the scheme design of the switching module with multi-protocol conversion function and the advantages of quick conversion rate, meets all existing agreements mutual conversion function, and adapts to a variety of safety monitoring system; and their own video access interface can be realized without changing the existing network structure and without the basis of the net again, which meets the existing substation monitoring and control system for accessing to the functions of the video transmission.