Usually the aquifer is above or below the coal seam, for the first time, the mining coal seam is found as the main aquifer in Xiaojihan Coal Mine of China's western Yuheng Mining Area. In this paper, we studied the mechanical properties of the water bearing coal seam in Xiaojihan Coal Mine. Based on the study of strength characteristics of water bearing coal seam, its special mechanical characteristics which are different from the other seams are obtained. Through uniaxial compression test, triaxial compression test and split test, the parameters such as the compressive strength, elastic modulus, Poisson rate, tensile strength and internal friction angle of each rock stratum are obtained. The research shows that the tensile strength and internal friction angle of the coal specimens from the water bearing coal seam are lower than that from the other rock strata. These mechanical properties indicate that the structure of coal seam is loose and it contains a large number of pores and has good permeability. Therefore the coal seams of Xiaojihan Mine Coal posses the aquifer condition. The obtained mechanical properties provided a reliable theoretical basis for forecasting mining face and mine water inflow, for establishing the early pre-warning system of mine water disaster, for designing and optimizing the technology of driving and coal mining related with water disaster prevention.