Abstract: Soil salinization is considered the most important degraded soils that limit soil productivity, food security and ecosystems worldwide. There are a large area of saline-alkaline soils in the world, so they are the most important marginal land resources. In recent years, biochar has shown great application potential in soil structure improvement, soil fertility improvement, carbon sequestration and emission reduction. Recent studies have shown that the application of biochar can improve soil physical and chemical properties, carbon content and promote plant growth, and can be used as an effective measure for saline-alkaline land improvement. However, the effects of biochar on saline-alkali soil improvement and plant growth are complex and need to be further studied and summarized. Therefore, the effects of biochar on physicochemical properties, nutrient utilization, soil biological activity and plant growth in saline-alkaline soil were reviewed and discussed in this paper. Additionally, the improvement effect and its possible mechanisms for biochar on saline-alkaline soil and potential mechanisms of improvement on plant growth were systematically analyzed and summarized. This review would provide a reference for the applying biochar in saline-alkaline soil’s improvement and efficient utilization.