In order to investigate the effects of L-tryptophan and melatonin for the serum glucose level and antioxidant capacity in the hepatopancreas of Chinese mitten crab (Eriocheir sinensis). The female crab with the average body weight of (16.58±2.20)g were randomly allocated into 8 groups (the processing experiments of L-tryptophan and melatonin had 4 groups respectively). Each experimental period was 30 d. (1)The feeding experiment of L-tryptophan: crabs were fed with diet which added 4 levels of L- tryptophan, and the L-tryptophan account for the diet were 0.36% (basal diet namely control group), 0.47%, 0.73% and 1.05% (named diet 1, 2, 3 and 4, respectively). The serum glucose level and T-AOC and the capacity of SOD in the hepatopancreas were determined. (2)The injection experiment of melatonin: on the 1st and 15th day, crabs were injected with saline(control group namely C)and different doses of melatonin which were 10-6 mol/crab (μM), 10-9 mol/crab (nM) and 10-12 mol/crab (pM). Then the haemolymph and hepatopancreas were collected separately for the determination of the serum glucose level and T-AOC and the capacity of SOD in the hepatopancreas on the 1st and 15th day. In addition, we analyzed the serum glucose level on the 30th day. The results showed that different levels of L-tryptophan had no significant effect on serum glucose level, its value was approximately 4.62±0.20mmol/L. The diet which contained 0.73% L-tryptophan could significantly increase the capacity of SOD (82.86±1.07)U/mL. Injection of melatonin into crabs resulted in hyperglycemia in a dose-dependent manner on the 1st day. Among them, the serum glucose level of μM reached up to (7.56±0.36)mmol/L, which was significantly higher than other three groups. Moreover, the injection of MT played an important role in promoting the T-AOC and the capacity of SOD, but only occurred on the 1st day. Comparing with C, pM and nM, the the T-AOC and the capacity of SOD of μM was higher than them significantly. In summary, 0.73% L-tryptophan can improve the capacity of antioxidant of crabs, but the effects on the serum glucose level are not obvious. The injection of 10-6mol/crab melatonin can improve the serum glucose level and antioxidant capacity of Chinese mitten crab in short time (1 d).