In order to meet the requirements of the maximum overload and buffer distance of the damper in the design, the particle swarm method is used to optimize the parameters of the viscous damper. The impact dynamics model of the viscous damper is established, the relationship between the parameters of the damper is determined, and the fitness function of the 2 design indexes with maximum acceleration and buffer distance is constructed. The particle swarm optimization algorithm is used to optimize the multi-parameters of the viscous buffer to obtain the optimal system. And determine the value of each parameter. The results show that this method can avoid the contradiction between the 2 factors of maximum displacement and acceleration in the design of the size of the viscous damper, and quickly determine the practical significance of each parameter.