The invention relates to a method and system for evaluating the aging state of oil paper insulation in a high-voltage current transformer. The method comprises: dielectric loss factor data of a pieceof oil paper at different test temperatures are obtained; polynomial equation fitting is carried out on the dielectric loss factor data to obtain a spectrum fitting curve; a slope function conformingto the spectrum fitting curve is established; the spectrum fitting curve is substituted into the slope function to obtain an extreme point; on the basis of a relationship between a frequency at whichthe extreme point is located and dielectric relaxation time, relaxation time activation energy of the oil paper is calculated; a moisture content of the oil paper is calculated and relaxation time activation energy of the oil paper under different water contents is calculated; according to the water content of the oil paper and the relaxation time activation energy, a quantitative representation relationship between the water content and the relaxation time activation energy is established; according to the quantitative representation relationship, oil paper insulation dielectric loss curve reduction equations at different water contents and different test temperatures are established and an oil paper insulation dielectric loss translation reduction curve under a low temperature is obtained; the obtained curve is compared with a practically measured curve and thus an aging state of oil paper insulation in a high-voltage current transformer is evaluated.