The whole process coordinated defense system of power system security and stability is put forward, and the overall framework and system functions of the proposed system are also designed. Take the four-grade warning and preventive control system of Henan power grid security and stability for example, the functions and applications of coordinated defense system are expounded during the whole process, including power grid repair plan arrangement, operation mode checking, scheduling operation and scheduling real-time monitoring. Finally, solutions of the key technologies during development and application are proposed.