Lipases from different resources exhibit three specificities for substrate glyceride:The acyl chain specificity for chain length,unsaturation degree,and positions of double bonds in glyceride;The positional specificity for the position of Sn-1(3)and Sn-2 ester bonds in glyceride;and The stereospecificity for enantiomorphous 1-and 3-ester bond of glyceride,Lipase catalyzes ester hydrolysis and esterification(or transesterification )to prepare monoglyceride,polyunsaturated fatty acid and its ester,and optically active organic compounds，thus it has great potential in fatty oil processing and organic synthesis.