In general, the performance of electronic products deteriorates before failure. But, the traditional life prediction method does not use the degradation information. The power supply module of electronic trip unit is taken as the research object, the correlation between the MOSFET switching period and the circuit weak link electrolytic capacitor degradation is analyzed, the MOSFET switching period is taken as the characteristic quantity of performance degradation of power supply module, and the performance degradation model of the power supply module of electronic trip unit is formulated with the MOSFET switching period as the characteristic parameter. The power supply module is divided into health state, attention state and danger state, and the health state transition graph. The calculation method of transition time is determined, and the health state evaluation model is formulated. The accelerated degradation experiment of the power module under temperature stress is implemented to evaluate the performance degradation model and health state evaluation model. It predicts that the average transfer time of the power supply module from the health state to the attention state is 3 906 days under 40℃ environment, and the average transfer time of the power supply module from the danger state is 9 296 days.