Discharge may take place in high voltage apparatuses in the form of void discharge, corona discharge and surface discharge. Understanding of the discharge is very important to know the condition of the insulation. Partial discharge (PD) current pulse waveforms contain essentially all the available information concerning the PD generation and thus the available information concerning the physical mechanism of degradation and breakdown of insulation. In this paper, three types of discharge model for polyethelene insulation material are constructed and the PD current pulse waveforms are extracted from experiments. In order to obtain pulse waveform characteristics, the extracted pulse waveforms are pre-selected and normalized, and then a Sampling Counting Ratio (SCR) classification technique is investigated to reveal the multi-peak and oscillation information about the PD current pulse waveforms. Results show that the classification would enable us to estimate the progress and degree of the degradation.