For the unloading sleeve of 1600 mm roll-forging machine, in order to meet the lightweight requirements under the condition of initial static stiffness, a multi-objective optimization design method taking mass and total deformation amount as objective functions was proposed. Then, the 3D model was imported into CAE software to establish the finite element model，and the static calculation was carried out to obtain the maximum equivalent stress of 74.735 MPa and the maximum deformation amount of 0.16299 mm. Furthermore, the parameters were selected by the response surface optimization to determine their value range, the test design table was generated through the central composite test method, and the response surface of design variables and objective functions according to the test points and the standard response surface method was established.Then the mass and maximum deformation amount of unloading sleeve was optimized by using the multi-objective genetic algorithm. According to the design requirements and practical experience, the candidate group Ⅲ was selected as the optimization result. And the calculated optimization result was modified by combining the sensitivity analysis. After the modification of unloading sleeve,the stiffness is increased by 0.8%, the maximum equivalent stress is reduced by 24%, the mass of unloading sleeve is reduced by 8.6%, and the comprehensive mass is reduced by 27.8%, meeting the requirements of lightweight.