Abstract: Battery is an important part of DC power supply system, providing a backup power supply for the DC power supply system and ensuring the safe and stable operation of the substation. Therefore, the battery is particularly important, and the size of the floating charging flow is closely related to the health status of the battery. Through the measurement and analysis of the floating charging flow of the battery, the problems existing in the DC power supply system can be found in time to reduce the risk of equipment. Through the measurement of the floating charging flow waveform of the first DC power supply system of the 220kV×× substation in our bureau, this paper analyzes and judges, and puts forward corresponding suggestions and improvement measures to provide reference for the study of such problems.