To satisfy the requirement of constructing coal mine integrated automation system, the paper develops a kind of multi-protocol Ethernet gateway which has the function of data pretreatment and protocol conversion. The paper firstly selects MOXA UC-7420 intelligent communication platform based on MontaVista Linux embedded OS as developing platform, and then programs the scheme based on multi-protocol Ethernet gateway aiming at connecting substation automation system to coal mine integrated automation system. Following, it expatiates the desigen scheme and realization of every primary module, the main structure of the application software centered the design and realization of the gateway application software. At last, the application of multi-protocol Ethernet gateway in field is introduced.