This paper puts forward the risk assessment of power system components method based on the risk theory. Based on the theory of risk, the impact of component outage probability and component outage on the system is considered comprehensively. Five categories of risk indicators, including risk of over-voltage, low-voltage risk, risk of circuit overload, transformer overload risk, and loss of load risk are used to diagnose the risk of power system components, the 3 scale analytic hierarchy process is applied to derive components integrated risk, and then the ALARP principle is used to quantify and classify the consolidated risk. IEEE RTS - 79 system verifies that risk assessment method of power system components based on risk theory is feasible. It can determine the risk level and importance degree in the system of each system component, providing a certain reference for power system operation maintenance personnel.