1 INTRODUCTION
The computer based interlocking system equipment of station is very important system which does matter with the rail operation safety. As an main control equipment of railway station, it plays an important role in ensuring railway safety, increasing working efficiency and improving operators working conditions. The interlocking system of station is a signal system of station for safe train running. An interlocking system control signals, turnout machine and rail approach according to a safe relations and operation order. Modern interlocking system have three kinds of instrument which are color signal lamps, circuits of railway and rail control machine as based equipments. As usual, it uses electronic instrument, for example relays, control these equipments as a totally control. The paper introduces the computer interlocking system with special structure of safe redundancy