Usually there are two methods to describe the characteristics of partial discharge. One is the method based on the statistical parameters of partial discharge signals, another is the method based on the shape parameter of a discharge pulse. The former means a statistical analysis technique for partial discharge signals and the common parameters include the discharge quantity, the inception voltage, the number of discharge, and so on. Especially,the maximum discharge magnitude is regarded as a standard of evaluating the status of partial discharge[']. The latter means an analysis method for the shape parameter of a discharge pulse, which includes the time-domain waveform and the frequency-domain waveform. The shape parameters include the waveform peek, the rising time of pulse, the descendent time of pulse, the width of discharge pulse, the duration of discharge, and so on. Moreover, the frequency waveform of the discharge pulse can be studied by a similar method. The discharge energy distribution in fiequency-domain can be obtained by the spectrum. These two methods are used at the same time in our research