Based on the Jiu-bao bridge seismic risk studies, the seismic standards and performance targets are analyzed, and the ground motion input was determined. A full-bridge finite element model was established. Dynamic characteristics of the main bridge and approach bridge were analyzed. Linear and nonlinear seismic response of the bridge considered unfavourable factors were analyzed by response spectrum and time history analysis method respectively. Key components of affecting design of the main bridge and approach bridge were checked. In connection with the foregoing results, an isolation measure in combination elastic cables with a friction sliding bearing with a shear bolt was putted forward, and the rational stiffness values of elastic cables and damping effects are analyzed. The results show that the rational design of elastic cables can significantly reduce the seismic forces demand of key components and ensure the seismic safety of the structure, meanwhile, the relative displacement of piers and beams induced by cutting off the bearings.