The fractal study of the lightning time domain waveform ignores its frequency characteristic,so that all the characteristics can not be fully characterized.In order to solve this problem,this paper introduces the multifractal theory into modern spectral estimation,and proposes a multifractal characteristic analysis and discharge type identification method of the lightning electric field signal based on auto-regressive (AR) spectrum.Firstly,the power spectrum of the lightning electric field signal is obtained based on the AR model spectrum estimation method.Then the multifractal detrended fluctuation analysis (MF-DFA) method is used to verify that the lightning AR spectrum sequence has multifractal characteristics,and the Hurst exponent and multifractal spectrum of AR spectrum sequence are further discussed.Finally,these parameters are input into support vector machine as the effective eigenvalues to identify different discharge types of intracloud lightning (IC) and cloud-to-ground lightning (CG).The experimental results show that the effective recognition rate of the proposed method reaches more than 94%.The research results have certain reference value for the research of lightning characteristics and automatic recognition technology.