The invention provides a power grid load loss risk assessment method based on a PSASP model and an emergency power supply automatic throw-in strategy. The method includes the steps of extracting a node card, a branch card and a virtual branch card of a PSASP load flow calculation model, establishing a mapping relation between emergency power supply automatic throw-in device action logic and the PSASP load flow calculation model, establishing an emergency power supply automatic throw-in device strategy simulation model configuration table and conducting power grid power supply load loss risk simulation assessment. According to the method, the problem that power grid power supply load loss risk cannot be accurately assessed in power grid operation research and analysis work is solved, previous power grid fault simulation analysis modes are changed, a powerful technological support is provided for simulation analysis work of faults of a power grid N-1, a power grid N-2, important transmission sections and the like, and power grid potential safety hazard checking and controlling are analyzed more accurately and effectively.