The main functions, key technologies and performance indicators of the on-line security and stability analysis with pre-alarm and decision-making supporting system for regional power grids are recommended in real-time grid monitoring and real-time pre-alarm. The development background of the field of dynamic security analysis of power network is analyzed, and the feasibility of regional power network security and stability is proposed. The system reads on-line data from SCADA/EMS and rapidly identifies all kinds of potential safety problems and the abnormal information from the model of power grids with the use of distributed parallel computing platform, it can quickly find out all kinds of potential safety problems, give a comprehensive intelligent alarm information, and provide accurate alarm correct treatment strategies for dispatch staff to adjust the different degrees of control center of information integration. The system is verified by power development and implementation in Luoyang, which not only greatly improves local grid real-time safety early warning ability, but also enhances the accuracy of the system model by finding data errors and abnormal information from the local power grid model. It has been proved that, this system is an essential tool for the future development of the regional power grid.