Abstract: Model tests on a geosynthetic-reinforced slope in macro- and meso-scale are performed to investigate its deformation models, meso-interaction between geosynthetic and soil particles, particle movement in the shear zone, as well as macro- mesoscopic mechanism. Because of the geosynthetic in the sand slope, a shear zone in arc occurs just like the failure surface mode of clay slope in macro-scale. Three stages can be found in the p-s curve of foundation: elastic stage, elastic-plastic stage and plastic stage. The transformation of p-s curve relates to the development of the main shear zone. The “cohesion” in the sand slope is provided by friction and occlusive force in the interface between sand particle and geosynthetic in meso-scale. The whole sliding resistance is composed by the friction in the “main shear zone”, “transitional zone” and “steady zone”. The intrinsic factors which form and change the failure surface of the geosynthetic-reinforced slope are the “cohesion” provided by friction and occlusive force in the interface between sand particle and geosynthetic and the friction force during the development of whole shear zone.