Abstract: It was found from the determination of the collapsibility of loess that there is a downward attenuation of collapsibility due to overweight or vertical fluctuation of collapsibi lity due to the degree of pedogenesis.The microstructure of loess is divided into 18 types on the basis of the microscopic study and the correlation between collapsibility and pedogenesis.It is thus known that collapsibility only occurs in some specific soils during pedogenesis,e.g.the brown soil,Chestnut soil,Sieronems,Chernozems,Loessial Soil and Drab Soil of CaCO₃ that have experienced poor pedogenesis.No collapsibility occurs in wet soils that have undergone strong pedogenesis.