Abstract: The immobilized Candida sp.lipase was used as the catalyst of transesterification to prepare glycerides which contained 45% DHA and EPA totally.Transesterification was carried out with fish oil ethyl esters and triglycerides as substrates.The effect on transesterification of temperature, reaction time, enzyme dosage, substrate weight ratio and water dosage were investigated with 5g glycerides as one of the substrates.The favorable conditions obtained were:reaction temperature 60℃, reaction time 24h, the substrate weight ratio 5:4, enzyme dosage 80U, without adding water to the reaction system.Under these conditions, the glycerides obtained contained 33.40% EPA and 13.10% DHA, and the immobilized enzyme could be used for seven times.