In view of the challenges faced by the electric power dispatching center that cannot fully monitor and control risks affecting the safety of power system，a design scheme of security risk management system（SRMS）is proposed based on risk management method.The flow chart and multi-time scale paradigm mechanism of security risk management are explained for power system dispatching and operation.The software architecture and key functions of SRMS are then designed.Preliminary application of SRMS in Hunan Electric Power Dispatching Center is finally described.