Abstract: In view of the background that most of the existing 500 k V /220 k V power grid partition methods are achieved by disconnecting certain circuits with little, if any, quantitative research on 500 k V /220 k V grid partition structure as a whole reported. A method of changing the power structure to predict the short-circuit current by solving the fractal dimension of the geographical wiring diagram is proposed. A quantitative research on the fractal dimension of a 500 k V /220 k V power grid structure is presented using the box dimension programmed by MATLAB calculations program while the short-circuit current basic model is studied, based on which the mathematical relation between power structure and short-circuit current is developed and the prediction of short-circuit current is achieved. Finally, an application example is given to prove the effectiveness of the proposed method.