The invention discloses a capacitor voltage transformer operation performance variation trend prediction method and system. The method comprises the following steps: acquiring environmental parametervalues and performance parameter values of a capacitor voltage transformer; grouping the acquired environmental parameter values and performance parameter values by group; establishing a first again-regression equation between environmental parameters and performance parameters on the basis of the grouped parameter values and performance parameter values, and extracting environmental parameter coefficients of the same environmental parameter in the first again-regression equation in different time windows, thus forming an environmental parameter coefficient set; according to the environmentalparameter coefficient set, establishing a second again-regression equation between the environmental parameter coefficients and the time windows, and obtaining the performance parameter value of the capacitor voltage transformer according to the first again-regression equation and the second again-regression equation, thus performance of the capacitor voltage transformer is predicted. The capacitor voltage transformer operation performance variation trend prediction method and system which are provided by the invention can realize prediction on an operation performance variation trend of the capacitor voltage transformer.