Shear tests along bedding plane on Guzhu expressway schist under natural state and water-saturated state have been carried out in order to analyze the shear strength characteristics of the water-sensitive schist located in northwest of Hubei province under the two states. The results show that：compared with the native state

the cohesion force of the schist under saturation state decreased by 36.7%; the internal frictional angle decreased by 4.6%; the residual cohesion force decreased by 66.7%; the residual internal frictional angle decreased by 11.3%; it is different from the brittle fracture under natural state that the schist shows obvious characteristic of ductility at failure under saturation state. Based on the experimental results，the water weakening mechanism of shear strength parameters of schist has been discussed; a safety factor of a slope located in Guzhu expressway has been computed with limit equilibrium method; and then the evaluation of the slope stability under storm or continuous rainfall conditions has been made.