Abstract：The characteristics of fluid flow in fractured rock masses are more complex than general porous medium flow in virtue of randomness，fuzziness of mechanical parameters and corresponding complex geomechanical environment. However，geotechnical engineering design，performance and safety assessment are often involved in fluid flow and hydro-mechanical coupling of fractured rock masses，making hydro-mechanical coupling of fractured rock masses being hot in mechanical investigation. In recent years，some advancements are achieved in saturated hydro-mechanical coupling，but saturated flow cannot be adopted simply in many practical projects. Therefore，most important influences of unsaturated hydro-mechanical coupling in fractured rock mass on strength and stability of the rock projects should be considered. Investigating productions for hydro-mechanical coupling of fractured rock masses by a good many scholars were generalized；and unsaturated hydro-mechanical coupling analysis model based on discontinuous medium method was put forward according to the mechanical calculation theory of discontinuous deformation analysis(DDA) and unsaturated fluid flow analysis. Taking reservoir rock slope as an example，the stability of rock slope was discussed with rainfall. The results indicate that rock slope stability is greatly reduced with increase of infiltration time of rainfall. The greater rainfall intensity is，the more greatly the stability coefficient of rock slope is reduced. Especially，the stability of the rock slope with/without considering coupling was different：the greater rainfall intensity was，the greater difference between two cases was. The calculation results achieved by numerical simulation and practical projects application agree well with those of in-situ tests，which illuminates that hydro-mechanical coupling model could reflect hydraulic characteristics of fractured rock masses. It is proven that the numerical model is feasible and valid in practical projects.
