Abstract: In order to carry out the experimental study of the mechanical properties of sandstone under water effect, the uniaxial compression test and point load test of the roof and floor of 2# coal were carried out under the water effect.The results showed that the water effect had a significant impact on the uniaxial compression and point load test.The linear deformation of the stress-strain curve of the saturated specimen gradually changes to nonlinear deformation in the stages of compaction and elastic deformation, and the occupancy time increases significantly, and the curve time is short and rapidly decreases in the stage of rupture development.The compressive strength of point-load dry specimens is higher than that of wet specimens.The uniaxial compression and point load rupture patterns of the roof and floor change with different water effects.After the compression specimen is subjected to the action of water, the internal structure is damaged, the cohesion is reduced, the plastic deformation increases, the brittleness is reduced, the internal shear stress reaches its ultimate strength before the tensile stress in the compression process, and the tensile and shear failure changes to shear failure, and the point load specimen changes from brittle failure to plastic failure under the action of water.The uniaxial compressive strength and point load strength of the roof and floor decreased under the water effect, and the compressive strength and elastic modulus of the wet sample of the bfloor decreased by 6.69% and 6.70%,respectively, compared with the dry sample in the uniaxial compressive test.Poisson's ratio reduced by 20%.The compressive strength of the wet roof sample is reduced by 20% compared with the dry sample; In the point load test, the average compressive strength of the dry sample was 50.06 MPa, and the average compressive strength of the wet sample was 42.19 MPa, which was 15.7% lower than that of the dry sample.