Mechanical parameters were obtained by mechanical test to obtain the mechanical properties of overlying strata in coal seam. Test results show that natural density, tensile strength, uniaxial compressive strength and the elastic modulus of the samples increase with the raise of the occurrence depth while water absorption rate and Poisson's ratio decrease with the increase of the occurrence depth, and the mechanical properties of the specimen are directly related to the lithology. Discreteness of test data increases with the increase of the occurrence depth. In addition to tectonic stress, coal mining and temperature effects, the main reason for discreteness is that the internal particles of the sandstone and other sedimentary rocks recouple with the stress relief.