The study was conducted to explore the effect of proteoglycan Z0206 on immunomodulation in rats. Forty SD rats were randomly divided into four groups. Rats in control group were fed basal diet, and those in experimental groups were fed basal diets supplemented with 0.2%, 0.4% and 0.8% proteoglycan Z0206, respectively. The results showed that the spleen and thymus indices of rats in 0.4% and 0.8% groups were significantly increased (P<0.01). The concentrations of IgA, IgG and IgM in 0.4% group were significantly increased compared with the control group (P<0.05). Serum C3 concentration and lysozyme activity in all experimental groups were significantly increased (P<0.05). Secretions of TNF-α, IL-2 and IL-6 in rat in 0.2% and 0.4% groups were significantly increased (P<0.01), and concentrations of the above mentioned cytokines in 0.8% group were higher than those in control group (P>0.05), but lower than those in 0.4% group (P>0.05). In conclusion, the proteoglycan Z0206 can enhance immune function of SD rats, and the best supplementation level is 0.4%.［Chinese Journal of Animal Nutrition, 2010，22（5）:1350-1354］