The composition of fatty acids and lipid content during embryonic development of fresh prawn Macrobrachium rosenbergii were determined by biochemical methods. The results showed that content of total lipid decreased significantly during development. There was a similar tendency in neutral lipid content, while content of phospholipids nearly remained constant. Higher utilization of total lipid indicated that lipid in embryos of M. rosenbergiiwere used mainly as an energy source. The quantitatively most important fatty acids were the saturates (SFA):C14:0，C16:0，C18:0, the monounsaturates (MUFA): C16:1n-6，C18:1n-9, the polyunsaturates (PUFA)comprise C18:2n-6，C20:4n-6 (ARA) and n-3 high polyunsaturates (ω-HUFA) C18:3n-3，C20:5n-3(EPA) and C22:6n-3(DHA).C18:1n-9 and C16:0 were main energy resources during embryonic development of Macrobrachium rosenbergii. Different fatty acids acted as main energy source during different embryonic stages. The saturates and the monounsaturates were main energy source from fertilized egg stage to gastrula stage. The monounsaturates were main energy source from blastula stage to egg metanauplius stage and so did the polyunsaturates from nauplius stage to zoea stage.