Based on the rock type of coal-bearing formation，the key factors to control rock mechanics properties，such as lithological characters，in-situ stresses, and moisture, are systematically analyzed. The mechanical characters of different rocks under different confining pressures and moistures are studied. The quantitative relationships between the rock mechanics properties and lithological characters，in-situ stresss and moistures are established，respectively. It is shown that the strength and stiffness of rocks are rapidly reduced with decrement of the grain diameter，namely from sandstone to mudstone. The stiffness and strength of different rocks increase with confining pressure. The behavior of the strain softening and failure mechanism of different rocks are transformed with the increment of confining pressure. Moisture influences the rock mechanics properties evidently. Under the dry condition or low moisture，rock reveals the attributes of brittle and shear fracture after peak strength. From the stress-strain curves，the strain softening characters are evidently shown. With the increment of moisture，the uniaxial compressive strength and elastic modulus of the rocks decrease remarkably，and plastic failure is the main evidence，but the properties of strain softening is not so remarkable.