The invention discloses a method for treating and improving saline-alkali soil. The technical scheme essentials include the steps of uniformly mixing a soil conditioner and a soil improvement agent, uniformly scattering the mixture on the surface of the saline-alkali soil, plowing the saline-alkali soil after standing treatment, and then conducting irrigation to eliminate salt, wherein the soil conditioner includes furfural residue, peat, animal waste, traditional Chinese medicine residue, sodium alginate, fulvic acid, a biological bacterium agent and water; and the soil improvement agent includes phosphogypsum, calcium superphosphate, polyacrylamide, lauryl alcohol phosphoric acid ester potassium, potassium dihydrogen phosphate, meerschaum powder, diatomite, attapulgite, bamboo fibers, sodium lignosulfonate and water. According to the invention, the soil conditioner and the soil improvement agent are applied to the saline-alkali soil, so that the salinity and pH-value of the soil arereduced, the soil fertility is increased, the soil structure is improved, the salt return of the plough layer is alleviated, the emergence rate of crops is improved, and the treatment efficiency is improved.