The invention discloses an anti-thunder optimum design method of a combined type composite tower. The anti-thunder optimum design method of the combined type composite tower comprises the following steps of (1) acquiring the structural information of the tower; (2) establishing wave impedance models of a ground electrode cross arm and a tower body and establishing a segmented lumped inductor models of a down conductor; (3) determining a path with the possibility of flashover according to the structure of a tower head and establishing an insulation flashover model based on a leading method; (4) establishing a ground resistor model under the condition that a lightning current impact effect is considered; (5) connecting the models to obtain a lightning stroke simulation model of the integral-basis composite tower; (6) calculating lightning withstand level and lightning trip-out rate; and (7) performing iterative computation and updating parameters. The geometric structure of the composite tower can be continuously improved by an iterative means so that the technical economy of the composite tower is improved on the premise that the lightning withstand property is guaranteed.