Abstract: The experiment was conducted to determine the effect of astragalus polysaccharides (APS) on growth performance,body composition and activities of immunoenzyme in Schizothorax prenanti. 450 healthy Schizothoraxprenanti with (6.98±0.43) g of average weight and (9.11±0.25) cm of average length, were randomly divided into fivegroups with three replicates of 30 Schizothorax prenanti. Group C1, as the control group, was fed with the basal diet(38.29% CP and 15.73 mJ/kg GE), while group C2, C3, C4 and C5, as trial groups, were fed with the diet added with0.02, 0.04, 0.06 and 0.08% APS respectively. The experiment lasted for 50 days. The results showed that the weight gainratio (WGR), specific growth ratio (SGR) and protein efficiency ratio (PER) of the fish fed with the diet added with APSsignificantly increased (P0.05), at the same time, the feed conversion ratio (FCR) of the fish significantly decreased(P0.05). All of the WGR, SGR and PER of Schizothorax prenanti were the highest (110.31%, 1.86%/d, 182.07% respectively),but the FCR was the lowest (1.44). when APS levels were 0.04%, those were significance difference withother groups (P0.05). Based on Linear and parabolic regression analysis of the WGR, SGR, PER, FCR, the optimalAPS level for the diet was 0.045%—0.074%; moisture crude Ash in whole body of Schizothorax prenanti showed nosignificant effects by supplemental levels of APS (P0.05), but the crude protein was the highest at 0.06% APS, whichshowed no significantly difference from that of 0.04% APS (P0.05), and the crude lipid was the highest at 0.04% APS,which was significantly different from other groups (P0.05); Activities of immunoenzyme in Schizothorax prenanti oftrial groups were significantly higher than those of control group, and the activities of immunoenzyme increased withthe increment of APS level in certain range. Schizothorax prenanti had the highest alkaline phosphatase activity (ALP)when fed with 0.04% APS, at the same time, the acid phosphatase activity (ACP) were the highest when fed with 0.06%APS. Lysozyme (LSZ) and superoxide dismutase (SOD) activity tended to stabilize when 0.06%—0.08% APS were fed.Results of above showed that the addition of APS could promote the growth and immunity of Schizothorax prenanti.The optimal dietary APS levels for optimum growth performance and immunological indices in Schizothorax prenantiwas suggested to be 0.04%—0.074%.