Water content has an important influence on the mechanical properties of coal. In order to further explore the mechanism of water content in coal mechanics under triaxial loading conditions, representative coal samples in Pingdingshan mining area were selected and experimental groups with different water content levels were set up. Uniaxial compression tests of coal samples with different water contents and triaxial compression tests of coal samples with different confining pressures were carried out, and comprehensive performance tests of stress-strain relationship and compressive strength of coal samples with different water contents were carried out. The results show that under different confining pressure conditions, the stress-strain curve of water-bearing coal shows the same trend. Under the condition of triaxial loading, the stress-strain curve in the axial direction of water-bearing coal body is the same as that in the axial direction of coal body under uniaxial loading. Under the same water content condition, the axial strain of the test coal samples with different confining pressures is slightly different when the stress peak appears. The larger the confining pressure, the smaller the axial strain corresponding to the stress peak. During the whole loading process, the axial strain of the test coal sample is always positive, that is, the axial compression deformation of the coal body occurs in the axial direction, and at the same time, the radial expansion deformation of the test coal sample occurs. Under uniaxial / triaxial loading conditions, with the increase of water content, the peak strength decreases as a whole, and the relationship between water content and peak strength is a quadratic function. With the increase of confining pressure, the peak strength is as a whole.