This paper studies the lightning hazard distribution maps and lightning strike quantitative calculation methods which are commonly used for lightning risk evaluation of overhead transmission presently, in view of the deficiency of those two methods, the “tower-tower section-line” differentiation and multi-level evaluation model is proposed. The density of ground lightning serves as the evaluation index in the proposed model. Also, the model takes the lightning withstand level of transmission line, the surrounding topography and history of lightning trip out accidents into account. According to the model, the risk grade of each tower is calculated and divided to determine the tower section that is easy to flashover. And then the paper evaluates the influence coefficient of the risk section to the whole transmission line based on the analytic hierarchy method. Accordingly, the comprehensive risk assessment of lightning for the whole line is evaluated step by step. Finally, the feasibility of this evaluation model is verified by a practical case.