The comprehensive monitoring, analysis, and diagnosis of power operation equipment have always been problems that the power sector is looking forward to solving. In particular, the accumulation of transformer operation management experience has provided a considerable amount of domain expertise and fault symptoms for the establishment of the power transformer insulation diagnosis expert system. It has been able to gradually carry out analysis, judgment, and decision-making research on the fault and life of the operating equipment, so as to reach the status Monitoring and diagnosis, the purpose of establishing a predictive maintenance system. On-line monitoring of power transformers is an important means to reflect the operating status of equipment in a timely and accurate manner. Partial discharge detection of transformers and chromatographic analysis of gas in oil are the main methods to reflect the insulation status during operation.