The random disturbance with strong impact and strong time variation, when the matrix AC charging pile is charged, leads to the inaccurate measurement in the electric energy metering period. Therefore, this paper puts forward a mathematical model of power grid energy metering based on Wiener functional series. Using the model can optimize the output voltage and current synchronously. At the same time, it uses the wavelet algorithm to decompose and reconstruct the voltage and current signals to get the fundamental component and the distortion component required by power flow analysis, and carries out experimental analysis on power flow of voltage and current mutation combining with the definition of IEEE-Std1459-2010. The correctness of model is verified through Matlab simulation. The experimental results show that the error of this method in AC charging pile of electric energy metering reaches to 0.001 orders of magnitude, which improves the measurement accuracy of AC charging pile and effectively solves the problem of the inaccurate energy measurement of AC charging pile under the condition of random disturbance. This work is supported by Science and Talents Program of Education Department of Heilongjiang Province (No. 12541136).