Abstract: The standard metabolism of the juvenile Eriocheir sinensis collected from Shanghai were studied under their non-feeding and resting conditions from Oct.to Dec.of 1998 and 1999,respectively.The results showed that oxygen consumption,CO2 production and ammonia-N excretion of the juvenile crab weight (2.70±1.40)g were (0.414±0.091)mg·g-1·h-1,(0.476±0.125)mg·g-1·h-1 and (4.179±1.171)μg·g-1·h-1 at (20±0.5)℃,respectively.Respiratory quotients,oxygen-nitrogen ratio and metabolic substrate ratio were used to describe the substrate metabolism of crabs.It indicated that oxidation of lipid dominated energy metabolism while carbohydrate and protein were the second and the third sources of energy metabolism,and energy ratio of protein,carbohydrate and lipid in metabolic substrate of the crabs was 7.3∶38.8∶53.9.The rate of oxygen consumption of juvenile crabs (R0) was remarkably affected by the level of oxygen dissolved in water,and negatively correlated with the body weight (W) of the crabs (R0=0.8403W-0.7265,n=33,r=-0.9097,P<0.01).