As a special soil widely distributed in the southeast coastal areas of China, granite residual soil is greatly influenced by water, leading to significant changes in its mechanical properties and an increased susceptibility to disasters. To investigate the shear characteristics of the granite residual soil-geotextile interface, the effects of different moisture content (12%, 16%, 20%, 24%) and vertical stresses (50 kPa, 100 kPa, 150 kPa, 200 kPa) were analyzed through large-scale direct shear tests conducted indoors. Based on the findings of indoor experiment, the PFC2D model was established, to reveal the meso-mechanism? behavior of the granite-residual soil-geotextile interface under varying moisture content conditions during the shear process. The results revealed that the interfacial shear strength and friction angle decreases with the increasing moisture content, while the similar cohesion increases first and then decreases, reaching the maximum value at 16% moisture content. Numerical simulation demonstrated that the shear zones are distributed in strips above the fabric, and the thickness of the shear bands increases in a predictable manner with the displacement field of the particles in the upper section.? The presence of the fabric prevents the penetration of force chains between the upper and lower sections, and the primary directions of normal and tangential contact forces remain consistent under different moisture content conditions. Energy dissipation mainly occurs through slip, with the loss of energy between the soil and fabric significantly lower than that between soil particles.