Abstract: In order to further study the precursory characteristics of deformation and failure of granite,the time-frequency domain information of the whole process of deformation and failure of granite is obtained by using the self-developed charge induction monitoring system,and the digital filter is designed to reduce the noise. The results show that the charge signal is generated in the process of rock deformation and failure. With the increase of loading rate,the energy accumulation accelerates. The shorter the time of energy accumulation for rock fracture,the earlier the high amplitude charge signal is generated,the more the number of stress adjustments,the higher the number of high amplitude pulse increase. Fourier transform and spectrum analysis of the signal show that the main frequency of the signal is in the range of 0～100 Hz. The frequency domain characteristics of rock deformation and failure generally show that the amplitude of the main frequency increases sharply when the stress drop occurs,and the amplitude of the main frequency increases most when the rock is completely destroyed. The increase of the amplitude of the main frequency and the amplitude of charge induction is synchronous. The sharp increase of the amplitude of the charge signal and the main frequency can be regarded as one of the precursors of rock instability and failure. A digital filter is designed to filter power frequency interference signal and high frequency noise signal,that could improves the accuracy of spectrum analysis.