Jinsha Jiang Bridge is located in the deep gorge of the Jinsha River Tiger Leaping Gorge town, a high seismic intensity area. According to the engineering geological conditions and the characteristics of joints, Barton model and shear stress test, strength parameters of rock mass structure surface are discussed. Then, the failure trend in gravity and engineering are analyzed by bottom friction test. The results have shown that the destruction of rock mass under the gravity and bridge foundation is mainly concentrated within 30 m depth of the slope. The slope under loading may cause loosening strength along joint planes. But under earthquake and bridge loads, bridge foundation should be strengthened.