Abstract: In order to accurately grasp the hydrologic characteristics of weakly cemented soft rocks in western China, the hydraulic and mechanical properties of red sandstone collected from northern Shaanxi mining area were tested. Based on the scanning image of scanning electron microscope(SEM), the mesostructural characteristics of the rocks were analyzed, and the relationship between the mesostructure of rocks and its macroscopic hydrologic characteristics was established. The results show that red sandstone has obvious characteristics of water saturation and water absorption and expansion, and its softening coefficient is 0.64. Under the action of pressure water erosion and dry and wet cycle, the properties of saturated red sandstone will be further degraded, which will be characterized by the decrease of strength and elastic modulus and the increase of mass loss rate. On the microscale, the relationship between red sandstone particles is relatively loose and has obvious weak cementitious structure characteristics. Generally speaking, the coupling effect of hydrophilic mineral dissolution and weak cementitious structure failure leads to the special macroscopic hydrologic characteristics of red sandstone. The results of this paper can provide certain theoretical support for the treatment and safe construction in weak cemented soft rock.