Esters is an important active aroma compound in Baijiu， and it has important impacts on the style and quality of Baijiu. Therefore， it is of great significance to study its formation mechanism in Baijiu brewing process. Systematic study and analysis of Baijiu brewing process showed that esters in Baijiu mainly came from enzyme-catalyzed reaction of acids and alcohols. Meanwhile， lipase， one of esterification enzyme， plays an important role in the reaction. Therefore， this study analyzes the formation of esters in Baijiu brewing process， and briefly introduces lipase and its catalytic mechanism of ester synthesis. The research progress and prospect of lipase for synthesizing of esters in Baijiu was discussed.