A conceptual model of soft rock in the red layer regions of China is developed with considering the softening characteristics and the mesoscopic images of the rock. Based on this, the characteristics of friction and contacts (including static and kinetic frictions) in the soft rock is analyzed. The maximum coefficient of static friction increases with the increase of actual contact area, normal stress and residence time, whereas the kinetic friction increases with the sudden increase of velocity. For the indirect contact particles, the tangential stress is mainly dependent on the shear strength of clay minerals which is dominated by the friction coefficient and adhesive strength. Furthermore, the water softening of skeleton particles is analyzed, it is found that hydration weakening effects mainly show as changing the contact stress between skeleton particles as well as degrading clay mineral particles, namely, the water reduces the effective stress between skeleton particle and clay mineral particle, and hence both the cohesion and internal friction angle of clay minerals. Owing to this, the friction between the particles and the strength of soft rocks decreases, and the soft rock becomes weaker. The above results can be reflected, to a certain extent, by the compression process of the soft rock under the triaxial compression test.