Norfloxacin, ofloxacin and enorfloxacin, the most common used quinolones in aquaculture, were evaluated for the effects on hemolymph enzymes of Chinese mitten crab, Eriocheir sinensis. The hemolymphs were collected at regular time for detection of phenoloxidase(PO), peroxidase(POD), alkaline phosphatase(ALP), lysozyme(LSZ), superoxide dismutase(SOD), glutamic-oxaloacetic transaminase(AST) and glutamic-pyruvic transaminase(ALT) after Chinese mitten crab were injected intramuscularly with quinolones at concentration of 5 μg/kg. The results showed that activity of PO, POD, ALP, LSZ and SOD increased respectively(P<0.05), and the effect of enorfloxacin experimental group was very obvious(P<0.01), and decreased to the normal levels as the control group at 96 h. The activity of AST and ALT after quinolones injection showed significantly lower during the experimental period(P<0.05). These results indicated that quinolones did not result in inhibition on hemolymph immune enzyme and damage on viscera organs. Moreover, quinolones showed immune enhancement on at concentration of 5 μg/kg.