This study was aimed to investigate the effects of dietary oligo-chitosan supplementation on growth performance, body composition, non-specific immunity, and antioxidant capacity of Eriocheir sinensis. A total of 288 crabs with uniform individuals [average initial weight (16.20±1.30) g] were allocated into 4 groups with 6 replicates of 12 crabs each, and fed a basal diet supplemented with 0 (control group), 25, 50, and 100 mg/kg oligo-chitosan, and the formal trial was 56 days. Compared with the control group, dietary supplementation with 50 and 100 mg/kg oligo-chitosan reduced the feed conversion ratio of E. sinensis and increased the edible visceral index. The inclusion of 50 mg/kg oligo-chitosan reduced the crude fat contents of the muscles and edible viscera, increased the superoxide dismutase and catalase activities of muscles and edible viscera. Compared with the control group, dietary supplementation with 50 mg/kg oligo-chitosan increased the alkaline phosphatase and phenoloxidase activities of E. sinensis. The results suggested that the addition of oligo-chitosan improved the growth performance, non-specific immunity, and antioxidant capacity, decreased the body fat deposition of E. sinensis. The effect is better when the dosage of oligo-chitosan inclusion in the diet is 50 mg/kg.