The problem of acidification in soil is widespread in China，causing serious impacts on the agricultural production and environmental safety.Biochar，as an excellent material for ameliorating acidic soils，has received extensive attention in recent years.However，there is relatively few studies on the effects and mechanism of biochar on ameliorating acidic soils.This article reviewed the research status of biochar in ameliorating acidic soil from three aspects including reducing acidity，improving the physical and chemical properties and biological characteristics of soil，and promoting the growth of crops.The mechanism of biochar reducing the acidity in soil including the binding of alkaline substances in biochar with H⁺，the esterification，adsorption and complexation of oxygen-containing function groups with exchangeable A1³⁺ in soil was clarified.The activities of microorganisms in soil were promoted by changing the environment in soil to regulate the growth of microorganisms in soil.The environment for the growth of crop roots was improved to increase the abundance of microbial communities of rhizosphere and regulate the development of root.The studies on the effects and mechanism of biochar on the amelioration of acidified soils were prospected to provide theoretical basis for alleviating the acidification in soils and promoting sustainable utilization of acidic soils.