In view of the difficulty in calculating the life cycle cost, a hierarchical calculation method is proposed based on the characteristics analysis of various costs for the main transformer. The proposed method obtains the basic data by the data fusion of PMS and ERP systems. Then, the regression analysis and blind number theory are introduced to calculate the mathematical model of life cycle cost for the main transformer. Considering the time value of funds, the net present value method in economics is utilized to classify the cost of each stage into the cost of the base year for analysis, which makes the model closer to the reality. Finally, 220 kV, 180 MV·A power transformer of two domestic and foreign manufacturers are taken as an example to analyze the specific calculation method of life cycle cost. The results show that the datadriven hierarchical calculation method is effective.