According to the theory of lightning leader, the influence of tower topography on the lightning risk of distribution lineis analyzed in this paper. Firstly, the tower elevation, ground inclination, soil resistivity and other parameters are applied to characterize the tower topography, and then the quantitative value assignment rules of provided parameters are established. Secondly, the BP artificial neural network classifier is constructed to classify the topography of distribution line towers in mountainous areas, which can meet the practical requirements of lightning risk identification of distribution line towers. The case application results are consistent with the actual situation. The proposed method provides a new idea for differential lightning protection of distribution lines in mountainous areas.