Granite residual soil is a kind of special soil, which is easy to induce geological disasters under the condition of heavy rainfall. Taking the mass landslides in Beiling area, Longchuan County, Guangdong Province as the background, the formation mechanism of typical landslides was explored by means of physical simulation, and the following conclusions were obtained: ① the influencing factors of landslides were rainfall intensity, physical and mechanical properties of rock and soil mass, slope structure; ② Rainfall does not cause the abnormal increase or decrease of soil pressure and pore water pressure in the slope, indicating that the failure of the slope is limited to the local failure of the slope surface and the slope toe, and there is no overall deformation and failure trend; ③ On the surface of the slope, the slope is eroded by rainfall, and on the foot of the slope, the free surface collapses and undergoes erosion. On the whole, the slope shows the characteristics of "step by step retreat and damage in turn"; ④ The evolutionary process of landslide can be divided into the following four stages: original slope evolution stage, soil particle migration stage, slope surface local failure stage and overall instability stage.