The invention aims to provide a collapsible loess foundation treatment method. A shallow-layer soil body and a deep-layer soil body of the foundation are reinforced, collapsing is eliminated, and then collapsing of the soil bodies is eliminated by adopting a water soaking method. The collapsible loess foundation treatment method includes the steps: 1), using a dynamic compaction method to ram a surface-layer soil body of the foundation; 2), uniformly forming pouring holes; 3), filling a bottom-end soil body for ramming; 4), pouring water and filling aggregate; 5), observing settlement until collapsing deformation is stable. In addition to the above objects, in order to further improve load-bearing capacity of a foundation soil body. The invention further provides another collapsible loess foundation treatment method. The treatment method includes the steps: 1), using a dynamic compaction method to ram a surface-layer soil body of the foundation; 2), uniformly forming pouring holes; 3), filling a bottom-end soil body for ramming; 4), pouring water and filling aggregate; 5), observing settlement until collapsing deformation is stable; 6), rearranging pile position points, and vibrating or hammering to form holes at certain depth; 7), filling fillers and ramming; 8), repeating filling and ramming operation until compaction pile bodies are formed.