To study the seismic design method for kilometer-scale cable-stayed bridge under near-fault impulse ground motion, a finite element model was established. The typical near-fault impulse ground motion was selected, and three damping systems were designed. The elastic connection device, the fluid viscous damper and the combination device of the two were used between the towers and beams respectively. Nonlinear dynamic analysis of the model was then carried out, based on which the impulse effect, the design parameters of the damping system and the damping effect were analyzed. The results show that the impulse long-period amplifies the structural response while the shear wave velocity has no effect on the structural response. In addition, the damping effect of the combination device is the best. Finally, the design flow chart for the damping system based on the target damping rate was proposed.