Abstract: Current transformers have evaluation criteria of different load levels, different current percentages and different error performance, which brings great difficulties to evaluate the performance of current transformers by analyzing error data. To avoid the trouble caused by the lack of unified standard caused by isolated analysis, a new analysis method based on the combination of principal component analysis and Copula function is proposed. First of all, the ratio error and phase Angle error of each brand of current transformer are measured under different current percentages through experiments, and the different current percentages that can reflect the overall level of the data are taken as evaluation indicators. Secondly, based on the principal component analysis method, the evaluation index is reduced, and the comprehensive evaluation value corresponding to the ratio error and phase Angle error is obtained. Then, based on kernel density estimation, the comprehensive evaluation value of ratio error and phase Angle error is obtained as the edge distribution function of Copula function, and the parameter values of common Copula function are obtained by means of maximum order estimation. Finally, the Copula function with the best fitting effect is determined by the optimal model selection criterion, and the mathematical expectation based on the Copula function is taken as the final evaluation standard. The experimental results show that the proposed evaluation method makes full use of the data information, the calculation is simple, and the performance evaluation of each brand current transformer is effectively realized.