For the purpose of reducing vibration of plate/shell structures with given dynamic stiffness, this paper put forward a bi-material topology optimization method for damping material layout on plates/shell under the premise of structure dynamic stiffness. The modal loss factor of the structure was taken as the design objective, natural vibration frequency was taken as constraints for the optimal design of bi-material damping layer, sensitivity expression of the objective function and constraint conditions were deduced, the mathematical model was solved by SIMP(Solid Isotropic Material with Penalization) and MMA(Method of Moving Asymptotes) methods. Studies showed that the optimal bi-material layer damping structure can effectively reducing the structural vibration level and noise compared with the single material layer damping structure, it could meet different engineering application requirements by changing the design objective and constraints. The optimal bi-material layer damping structure obtained by designing the layout of the two damping material, which one is high stiffness and low damping material, the other is low stiffness and high damping material.