Effect of overhead line corona interference on cable partial discharge detection in substation is serious, and correct understanding of characteristics of corona interference, establishing the corona characteristic library, excluding corona interference and improving cable partial discharge detection accuracy are of great significance. In this paper, results show that cluster analysis method, which use amplitude, rise time, fall time and maximum as parameters, is an effective way to pick up corona discharge and rule out interference from other signals also. Then corona interference waveform characteristics like rise time, polarity influence, spectral characteristics and interphase interference are focused on. Corona interference contains dense pulse, whose rise time is from 25ns to 175ns and fall time from 85ns to 230ns. Positive and negative pulses are of different trend as amplitude changes, when positive pulse length is lower than negative pulse. By spectrum analysising, we can find that frequency of corona pulse is between 1.25MHz and 2.5MHz. Corona pulse can interfere other phases, whose amplitude, rise time and frequency would change.
