The collapsing hill was a specific form of soil erosion in the granite red soil region of Southern China．It was one of the most important indications of serious soil erosion.As the material source of collapsing hill

the collapse of collapsing walls was the most active part of collapsing erosion. The soil disintegrating characteristics was an important indicator of the collapsing hill in southern China，and also the critical basis for soil conservation．In this paper

we used a combination of plot-based detailed representation and laboratory experiment based on broad field investigation to study the disintegration characteristics and the influence factors on different layers of collapsing wall. The results showed that: (1)The soil physico-chemical properties of the soil collapsing wall layer were closely related to the weathered degree of weathering mantle

and it showed some regularity. (2)At different levels of the initial soil moisture content

the order of the disintegration speedwas as the following：red soil layer