In signal collection process, useful signal usually mixes noise interference such as white noise, which usually causing error in computer analyzing and processing. At present, normal de-noising method includes hardware and software. This paper uses wavelet transformation software method, which realizing noise de-noising to electronic power signal. In wavelet analysis, suitable of threshold function selection defines signal de-noising effect directly. This paper adopts Matlab simulation, carrying out serial kinds of different wavelet basis selection, and adopting different threshold function, which getting different signal de-noising effect. This paper uses db24 wavelet and adopt heursure rule to complete electronic power signal's decomposition and reconstruction by Matlab software. From simulation we can see, wavelet filter and de-noising method is superior to other method in some non-stable signal process.