In order to improve the efficiency of PLC program debugging of vehicle storage system in a workshop,the simulation model of a conveyor car was created based on WinMOD system software platform,and connected with PLC controller to realize online virtual commissioning.The car model building,virtual commissioning environment building,communication interface configuration and online simulation were discussed.Practice has proved that TIA Botu and WinMOD joint virtual debugging can effectively reduce program errors,shorten the field commissioning time and reduce commissioning costs.