Abstract: In order to study the regularity of physico-chemical properties of soil column under continuous irrigation, reasonable application rate and irrigation amount of desulfuration gypsum and humic acid were determined. By using soil column simulation test, desulfurized gypsum was selected as modifiers. The leaching experiments of saline - alkali soil were carried out to analyze the relative indexes of soil and leachate.The results showed that Ca2＋ in desulfurized gypsum can replace the Na＋ adsorbed by soil colloid, adjust the ion balance, the effect was significant, and the desulfurization gypsum dosage 1.2 times of the theoretical value was more reasonable.