Abstract: A method for extracting and separating salt alkali from saline alkali soil and soil improvement is disclosed. A foundation pit, square convex edge and cylindrical partition are arranged on a saline alkali land. Nitric or phosphoric acid solution is added to obtain a saline alkali pool. A trench is set around, and/or, a cylinder is set in the center of saline alkali pool. The evaporating material is prepared from vermiculite, laid on plastic wrapping material, and/or added into the cylinder. The salt alkali is precipitated and enriched through natural evaporation. The evaporating material enriched with salt alkali is taken out to be dissolved, separated and washed to obtain saline alkali solution and vermiculite or evaporating material. The vermiculite material is returned for reuse, and the above process is repeated. Alkali solution and intercalation agent are added into saline alkali solution to react and crystallize to obtain functional materials.