Abstract: Several critical technologies of planning and scheduling including data modal, application frame of online simulation system and system integration were studied. The application of the object-oriented simulation system was proposed and implemented to solve the problems of system initialization and stochastic settings through online data exchange. It was discussed how to valid a shop floor production plan using online simulation, how to examine the robustness of a real-time production plan and how to readjust this plan. With the help of these results, reliable reference can be supplied for making decision on production planning in every period.