Partial Discharge (PD) detection after denoising, characterization and identification are the three main signal processing requirements of PD analysis. Voluminous digital PD data are nowadays readily available with constant improvements in PD measurement techniques. Power Engineers may be able to detect prominent PDs using oscilloscope and existing couplers. But identification of the types of developing and random occurring PD is a real challenge to any practicing engineer. In this thesis, details on using wavelet transform in the form of either continuous wavelet transform or discrete wavelet transform with two methods to denoise, identify the location of PD and retrieve PD wave shape without magnitude distortion are presented. To identify the type of PD, some experimental studies and about six existing and developed signal processing methods are carried out. Laboratory experimental study provided reproducible data with enough number of sampled points on three types of pure PD and one multisources PD.