Soil salinization seriously restricts the sustainable development of agriculture，but the application of modified biochar has a significant effect on the improvement of saline-alkali soil.In order to explore the mechanism of modified biochar improving saline-alkali soil.This article summarizes the effects of different modification methods on the physical and chemical properties of pristine biochar，as well as the improvement effect and influencing factors of modified biochar on saline-alkali soil.The results showed that the modified biochar had the characteristics of large specific surface area，many types and quantities of oxygen-containing functional groups，and a decrease in the proportion of alkaline substances.It can promote the formation of aggregate structure in saline-alkali soil，increase the adsorption of salt ions and nutrient retention，change the functional structure of soil microorganisms，and strengthen the ability of crops to cope with external stress.However，there were few studies on the long-term effects of modified biochar and the differences of its application in different types of saline-alkali soil.In the future，field verification tests of different types of saline-alkali soil should be carried out to explore the adsorption capacity and long-term effect of modified biochar on different salt ions，in order to optimize its improvement methods under different saline-alkali types.