Abstract: To investigate the security guarantee for the load power supply of key regional power grids under extreme weather, this paper proposes a load power supply guarantee strategy involving distributed power generation, energy storage, and electric vehicles in key regional power grids based on a situation awareness technology. The dispatching is optimized to ensure uninterrupted power supply for the power grids in key areas. First, in the situation awareness stage, information in the environment and grid operation status is collected. Second, in the situation understanding stage, the data collected by situation awareness is adopted to simulate power grid disasters to achieve in-depth perception of the power grid. Then, in the situation prediction stage, according to in-depth perception of the power grid, the distributed power output forecasting, energy storage electric rehicle station charging and discharging forecasting, and typhoon risk forecasting are adopted to carry out grid security risk assessment and early warning. Finally, in the situational guidance phase, comprehensive economic indicators and load shedding loss economic indicators for optimal dispatching were compared, considering, the load power supply guarantee cost and load loss cost to adjust the power supply guarantee strategy, and modified IEEE 33-bus system was used as an example for simulation analysis. Results show that the power supply guarantee strategy of key regional power grids based on situational awareness can effectively guarantee the load power supply in extreme weather. The results can provide a basis for power supply strategies in extreme weather.