Abstract: As one of the key equipment of high-speed trains, the accurate prediction of battery aging state is of great significance to the safe operation of high-speed trains. In view of the difficulty in online estimation of the aging state of the nickel-cadmium battery of CRH380 EMU, based on the maintenance procedures and health status indicators of the nickel-cadmium battery, the aging state of the battery at different temperatures and different service life conditions is studied, the aging mechanism and influencing factors of the nickel-cadmium battery are analyzed, and the relevant parameters of the nickel-cadmium battery are tested and analyzed. First of all, according to the standard maintenance procedures of nickel-cadmium battery, the experimental scheme is designed. Then, the capacity test and voltage test are carried out for Ni-Cd batteries with different repair procedures. Secondly, the aging characteristics under different conditions are analyzed through the obtained experimental data. The results show that there is a positive correlation between the aging state of the Ni-Cd battery and the battery temperature and the charge holding time.