In order to improve the dynamic stiffness of telescope mount, the accuracy of aiming and stability of optical system, a topology optimization method based on the theory of variable density and taking maximum stiffness as objective function is studied. In the topology optimization analysis of elevation ring, one of the most important members of the telescope mount, two kinds of structural are designed: one is a traditional plate welding structure and the other is a combination of plate welding and truss welding. Furthermore, the stiffness and modal performance of the elevation ring in different performances are analyzed and compared. The results show that in meeting the strength and stiffness of the premise, the mass of elevation ring with plate welding and truss welding is 7.00T and the moment of inertia is 11.94 t•m2. What`s more, the total deformation in the horizontal direction and the zenith direction are 6.70μm and 55.86μm, respectively; the stress is within stress range of material's promise; the modal is 105.9Hz.Compared with the traditional structural with plate welding, this new structural design approached to ensure the dynamic stiffness while effectively reducing its own weight with reduction rate 10.7% and moments of inertia with reduction rate 12.3%. This new structural of plate welding and truss welding has obvious advantages in lightweight design. This new design method based on topology optimization will provide efficient help to later components design of the telescope mount.