The invention relates to a method for improving soil saline alkali, belongs to the technical field of soil adjustment methods and mainly solves the problems of poor soil saline alkali improvement effects, small improvement saline alkali soil areas and low unit yields in the prior art. The method comprises fifteen steps of land flattening, seedling bed arranging, land leveling, alkali washing, alkali pressing, seed selection, seed sowing and seedling raising, greenhouse building, ventilation and temperature management, seedling water management, seedling pest control, land beating leveling, seedling transplanting, tillering stage management and booting and earing period management. By the aid of the method, by means of autotetraploid rice planting, water management strengthening, organic fertilizer increasing, integrated control of plant diseases and insect pests and land management, the soil saline alkali is improved apparently, the saline-alkali soil is improved in large area, and the yield per unit is high.