The invention discloses a distribution line flashover rate improvement algorithm based on an electrical geometric model, specific steps of solving the distribution line flashover rate by using the improved algorithm and considering factors such as lightning flashover density, tower shape, soil resistivity, line insulation level and other factors are proposed; the method comprises the following steps: determining line parameters, calculating a thunder-resistant level of direct lightning stroke, calculating equivalent flashover width of the line, and calculating the direct lightning stroke flashover rate and the inductive lightning flashover rate. According to the method, the influence of the lightning current amplitude on the equivalent lightning width of the line is considered based on theelectric geometric model, and the equivalent flashover width of the line is defined, so that the calculation of the distribution line flashover rate is more accurate, and the method has a certain guiding effect on lightning stroke risk assessment and differential lightning protection of the distribution line.