To meet the requirements of higher structural stiffness, higher vibration frequency, lower weight for the industrial robots, a method based on multi-objective topology optimization is presented. The method takes the deformation, vibration frequency, structure weight of the robot as the objective functions, and it optimizes the robot structure with topological method. Then, the method was applied to analyze and optimize a 3kg-load robot which has multi-function of assembly, transportation and so on. The results indicate that while the reduction of weight is 7.1%, the static deformation reduction is 22.4%, the first natural frequency is increased by 14.1%, the second natural frequency is increased by 14.2%, which fully verifies that the proposed method is available and effective.