Abstract: To ensure quality and safety, it is necessary to study the hydraulic features of soft rock. The hydraulic features of representative soft rock were studied by using the soft rock obtained in the water intake and outlet project of a nuclear power plant, conducting the slake durability test, the swelling test and the uniaxial compressive strength test. The experiment results show that the axial swelling rate of mudstone decreases linearly with increasing water content. The swelling pressure of mudstone decreases linearly with the increase of water content. The slake durability index of soft rock is mainly distributed between 30% and 60%, which belongs to low durability. Soft rock shows obvious softening phenomenon with water, and the strength decreases significantly. The test law has certain reference value for the project construction.