Abstract:As one of the most concerned problems in the engineering practice and the research field,the fault probability calculation of transformer is complex and practical.The paper analyzes the general research status of fault probability calculation.A comprehensive new calculation approach is put forward,by connecting the method fault tree analysis (FTA) and the equipment criteria evaluation.The transformer fault tree and the bottom events are analyzed based on FTA,and then evaluated after correlated with the equipment criteria,and the fuzzy comprehensive evaluation (FCE) method is used to calculate the weights of the criteria indexes before the fault probability formula model is finally established.In terms of an actual case,the application effect of the proposed method is verified.