Due to the poor elasticity of the existing transmission line tower materials, and the difficulty of applying the body structure to the geographical characteristics of the goaf, an optimization method of transmission line tower design for goaf is proposed. Firstly, a method of transmission line tower topology optimization is proposed. By choosing appropriate tower support form, edge form, inner layer number and redundancy number, the optimal tower structure is obtained. Then, fiber reinforced composite (FRP) is used to replace the traditional pole tower material to design the cross arm, so as to ensure that the pole tower is in the elastic working state and improve its bearing capacity. Finally, based on the back-tracking search algorithm (BSA), the optimization problem of tower topology is solved. Under the constraints of stress and displacement, the optimization of tower size, shape and topology is realized. Based on the finite element program developed in Matlab, the performance of the proposed method is demonstrated. The results show that compared with other methods, the structure weight of the proposed method is significantly reduced, and the structure is more elastic, which is suitable for the practical application of goaf.