According to the loads characteristics and working requirements of the rotor structure of the wheat peeler, the objective function, the design weight of the rotor, was solved under the constraints of input variables and state variables, here the structural parameters of the rotor were taken as the input variables, and the maximum deformation, natural frequency and maximum stress under the working load were taken as the state variables. The response surface method and the central composite design method were employed in the calculation. The numerical calculation experiment involves 150 sample points (groups), and three candidate points with composite state variable constraints were obtained. By this method, the maximum weight of the rotor can be reduced by 73.6 kg, the mass can be reduced by 35.16% compared with the original structure, and the maximum stress can be reduced by 12 MPa, meanwhile meeting the requirements of the structural strength, rigidity and dynamic stability of the whole machine. It shows that the lightweight design method can significantly reduce the quality of the peeling machine rotor on the premise of satisfying the performance of the machine.