The Paleogene strata is widely distributed in the tunnel of the Yellow River to Xining water diversion project in Qinghai Province， and the tunnel burial depth is deep. It is of great significance for tunnel design and construction to evaluate the deformation and stability of tunnel surrounding rock based on the study the physical mechanical characteristics of the Paleogene strata. In view of the stability of the surrounding rocks in Paleogene strata， A preliminary study on the physical mechanics of soft rock was conducted using experimental and empirical analysis methods. The results showed that the Paleogene strata has low density and high water absorption rate. Under saturated conditions， the uniaxial compressive strength of rocks decreases sharply， and the softening coefficient is extremely low； Some types of rock have expansibility and a small amount of rock has poor resistance to disintegration； The mechanical properties of the rock are poor under water-rich conditions， which is detrimental to the stability of the surrounding rocks. When the burial depth is over 127m， the surrounding rocks may undergo severe to extremely severe compression deformation. During the construction， targeted engineering measures should be taken based on the deformation characteristics of the surrounding rocks to reduce the hazard of surrounding rock deformation.