Based on particle flow theory, the process of formation, development, destruction and re-formation of the soil arching in loose media landslide were systematically studied by using PFC2D program to analyze the effect of meso-mechanical parameters such as friction coefficient and porosity on pile-soil interaction characteristics. The results show that the soil arching produced by the anti-slide pile for the first time bears the ultimate bearing capacity; after the destruction of the soil arching, subsequent formation of the soil arching effect bears the residual capacity; the value of residual capacity fluctuates, but within a certain limit; the ultimate bearing capacity, the residual capacity and the maximum pile load distribution ratio decrease with the increase of pile clear spacing, and increase with the increase of pile width, yet the relation is not a linear one; the soil arching effect is greatly affected by the friction coefficient within a certain limit, and as the friction coefficient increases, the effect is more significant, the ultimate bearing capacity of soil arching is larger, and the maximum pile load distribution ratio tends to increase; soil arching effect is significantly affected by the porosity of particle aggregate, and the soil arch ultimate bearing capacity of low density loose landslide is equivalent to the residual capacity of high density loose landslide.