The optimization of the elevation rotation structure (ERS) is one of the critical problems in the design of a large submillimeter telescope (LST). Here, combining the super element model with topology optimization method and genetic algorithm (SEMTOMGA) is proposed for the ERS design of an LST. The SEMTOMGA has three key steps: (1) the super element model is applied to condensing all the degrees of freedom of the large structure elements, which needs no topology optimization, except for the connecting nodes and the objective structure elements; (2) the topology method is applied to optimizing the objective structure; (3) based on the optimization results of the second step, the further whole structure optimization with multiobjective genetic algorithm(GA) is performed. The SEMTOMGA, which exploits the complementary merits of the super element model, topology optimization method, and GA, solves the problem of the ERS design effectively. As an application, a 60-m submillimeter telescope is designed and optimized by SEMTOMGA. The results have shown that the SEMTOMGA not only obtains a lightweight design of the ERS but also has sufficient stiffness. Moreover, the performance of the whole structure has been improved, and the residual half-path length errors of the main reflector have declined from 263.7 to 135.6  μm, which is about half of the original 263.7  μm of the initial design.