In order to study the effect of nonlinear viscous dampers on the seismic response of long- span cable-stayed bridge under different periodic seismic waves, as Erdong Yangtze River Bridge which main span is 926 meters in Hubei province of China for the research object, nonlinear viscous dampers are simulated by Maxwell model, and four viscous dampers are set at the joint of main tower and beam. The displacement and internal force responses of cable-stayed bridge with different velocity index and damping coefficient of nonlinear viscous dampers are analysed and discussed, in the situation of that long period and ordinary period seismic waves are input as earthquake motions. Analysis results show that: the displacement and internal force responses of long-span cable-stayed bridge under long period seismic wave are more negative; the displacements of key nodes of bridge can be reduced effectively by nonlinear viscous dampers; the internal force responses of bridge would be influenced greatly by the combination of different parameters of viscous dampers; the growth of shear and bending moment at the bottom of the tower can be controlled in an acceptable range by the reasonable parameter combination; the ideal parameter combination is that velocity index of viscous damper is 0.6 and the damping coefficient is 7000 N.(s/m)α for this cable-stayed bridge under long-period seismic wave.