Abstract: In order to solve the problem of solving the life index in corona resistance curve equation complicated and high precision, the corona resistance time of enameled wire under different impulse voltage was tested respectively, and Minitab software was used to analyze the curve equation of the optimal fitting relationship. The results showed that the corona resistance time and impulse voltage decreased exponentially and accorded with the exponential form with e base, meanwhile, Minitab can be used to predict intervals and the confidence interval of corona resistance time with 95% confidence, improving the accuracy and predictability of test results.