Most of the existing DC electricity meters are used to measure the DC steady-state energy, which has poor adaptability to the change of voltage and current during the charging process, and ignores the power generated by power fluctuation and high-frequency ripple. Therefore, by studying the principle of DC electric energy generation of rectifier load, switch charging equipment and fast dynamic load, combining with the metering algorithm and experiment of electricity meter, this paper expounds the error influence in the metering process, and puts forward the optimization method of calculation parameters to reduce the metering error in different metering occasions, which can provide reference for improving the accuracy of electric energy metering in different measurement occasions, provide ideas for the optimization of DC metering algorithm, and clarify the direction of improvement.