At present, a lot of researches have been carried out on harmonic energy metering technology, while there are few studies on energy metering technology under the influence of voltage fluctuation and flicker distortion signals. In this paper, the power mathematical model under the influence of voltage fluctuation and flicker is constructed, and the simplified calculation formula of power is deduced. The energy measurement method based on wavelet packet decomposition and reconstruction is proposed. The Db45 wavelet function and 5-layer wavelet packet transform is used to simulate the active energy and reactive energy measurement of steady-state and non-steady-state signals under the influence of voltage fluctuation and flicker. The simulation results demonstrate the feasibility and accuracy of the algorithm.