Infrared temperature measurement and ultra high frequency PD (Partial Discharge) detection are currently mature charged detection method. Infrared temperature measurement can make reliable prediction to electrical equipment fault and insulation performance; Ultra high frequency charged PD detection can effectively remove the influence of the interference signal, and reappear the pulse signal of the partial discharge, so that the type of the fault defects can be judged according to waveform characteristics. By use of various method of live line inspection, the traditional electrical equipment preventive test maintenance could be raised to predictable condition based maintenance, improving the pertinence and efficiency of the maintenance. Combined with the discovery and treatment of equipment defects, the effectiveness of various method of live line inspection to judge equipment defect was verified, which provided a reference to the advance of live line inspection level.