North China grid security constrained convention dispatch optimization system is designed integrated with energy management system（EMS）. The power network models gathered from EMS can be directly used in the system topology analysis. The distributed software design approach is used for easier development， maintenance and practicality. The security constrained unit commitment is used as the core to achieve annual generation contract scheduling， monthly generation contract scheduling， day-ahead generation scheduling and monthly energy market prototype. The security constrained unit commitment and units' parameters are considered in the optimization and the studied multi-timepoint AC network security check function is also used to guarantee the practicability and feasibility of the optimal results. All these functions are proven to be effective in the actual application.