This paper designs a Hanning self multiplication-convolution window function, which integrates the advantages of the self-multiplication window and self-convolution window and has better main-lobe and side-lobe performance. Based on the formula of self multiplication-convolution window FFT triple-spectrum-line interpolation correction, the frequency shift characteristics of FFT and the spectrum of the Hanning self multiplication-convolution window function, the fundamental and harmonic’s general amplitude, phase and frequency interpolation correction formula are given, and a new approach for electric energy measurement algorithm is also proposed. The experimental results based on calculation accuracy comparative simulation and fundamental frequency fluctuation simulation show that the new algorithm has better calculation accuracy and better calculation stability. This work is supported by National High-Tech R & D Program of China (863 Program) (No. 2015AA050404).