The invention discloses a method for evaluating an AC-side impedance balance index of a grid-connected photovoltaic inverter, and the method comprises the steps: building a time sequence of an AC-side impedance balance index evolution system for the grid-connected photovoltaic inverter; carrying out the normalization processing of measurement data according to the above time sequence; carrying out SVM (support vector machine) algorithm processing of the measurement data; and calculating the AC-side impedance balance index of the grid-connected photovoltaic inverter. Through the cooperation of the above four steps, the method can achieve the real-time monitoring of operation parameters and meteorological environment parameters of a power distribution network and a photovoltaic power generation system thereof, carries out the prediction and calculation of the AC-side impedance balance index of the grid-connected photovoltaic inverter according to the monitoring parameters, controls the photovoltaic power generation system and the power distribution network in real time according to a calculation result, can effectively solve a problem of power mismatching, caused by the access of a photovoltaic power station, of the power distribution network, and remarkably improves the reliability and economical performances of the power system of the power distribution network after the access of the photovoltaic system.