The invention discloses a thunder-proof planning method for an overhead distribution line in thunderstorm weather. The method comprises the following steps: (1) building an annual thunderstorm characteristic parameter random probability distribution model through annual thunderstorm characteristic parameters; (2) building a reliability parameter model of the overhead distribution line in the thunderstorm weather; (3) building a distribution network planning model for a thunderstorm disaster employing the insulator type and lightning arrester mounting intervals as decision variables; and (4) determining the models in the steps (1) to (3) through a genetic algorithm to obtain overhead distribution line insulator configuration and lightning arrester mounting interval data. According to the thunder-proof planning method, the technical problem that the overhead distribution line has a 'congenitally deficient' lightning-withstand level in design, is low in insulation level and is difficult to bear the effects of a direct lightning strike and an inductive thunder in thunder-proof planning of the distribution line in the prior art in power system planning, and the technical problems that the electricity demands of important loads in disastrous weather cannot be met due to a low line planning design standard, resources are wasted due to a high line design standard and the like are solved.