The main span of Hekou Bridge is 360m. It is the largest cable-stayed bridge in the earthquake zone with an earthquake intensity of 8 degrees and above in the country. It is equipped with liquid viscous dampers. It is a very effective energy dissipation device for semi-floating cable-stayed bridges. This paper introduces the setting form of the liquid viscous damper of the Hekou Bridge, focusing on the comparative analysis of the deformation and internal force effects of the key parts of the structure under the different conditions of the damping coefficient C and the velocity index α. The relevant parameters of the liquid viscous damper are optimized. . The calculation results show that by optimizing the damping parameters of the liquid viscous damper, the relative displacement and seismic force of the structure under earthquake action can be effectively reduced, and the seismic safety of the bridge can be improved.