Programmable　logic　controller　based　on　PC,　with　open　operation　architecture,　strong　ability　of　data　processing　and　good　network　communication,　is　a　new　type　control　technique　emerging　in　current　industry　automation　field,　and　can　meet　the　demands　of　open　and　flexible　control　system.　In　order　to　coordinate　with　Soft　PLC　developing　system　running　on　PC　to　carry　out　corresponding　control　function,　an　operating　system　of　Soft　PLC　is　designed　and　developed.　The　paper　briefly　describes　the　system　structure　of　soft　PLC　and　the　function　of　its　operation　system,　introduces　in　details　hardware　structure　and　development　process　of　its　operation　system,　and　provides　PCB　circuit　board.　In　circuit　design,　electromagnetism　compatibility　design　is　adopted　in　order　that　interference　between　signals　as　well　as　from　exterior　interference　source　is　reduced.　The　experiment　indicates　operation　system　designed　can　efficiently　fulfill　communication　and　control.