Abstract: In the report, based on the wavelet analysis method, the error control and selection of threshold method of even kinds of wavelet functions were compared, and the calculation results of S_NR and mean square error were used as the reference, the more reasonable Rigrsure threshold analysis method and sym5 wavelet function were selected as the de-noising method for ground atmospheric electric field signal. The method not only smooth the waveform of electric field signal and reduce noise signal mixed into electric field waveform significantly, but also keep the characteristic of fast change of electric field caused by lightning flash. Based on it, the difference calculation method was used to realize the function of automatic recognition of lightning signals from the electric field waveform. Two reference values, the total lightning frequency error and the correlation coefficient between automatic recognition and manual analysis results in a continuous time range, were introduced to select the electric field difference threshold in the differential calculation method, which can extract the information about lightning frequency and lightning polarity.