This experiment was conducted on healthy Pelteobagrus fulvidraco to study the effects of mannan oligosaccharides on non-specific immune function and the growth.The experimental fishes were divided into five groups.There are three replicates for each group.The control group(C) contained no mannan oligosaccharides,the treatment groups(KM0.1,KM0.2,KM0.3,M0.3) were contained 0.1%,0.2%,0.3% of konjac mannan oligosaccharides(Kon-Mos) and 0.3% of yeast cell wall mannan oligosaccharides,respectively.The results showed that:between 14 and 28 day,the phagocytic activity of leukocytes in group KM0.2 were significantly higher than the control group(P<0.05),phagocytic percentage and phagocytic index reached to the top level on the 14 d,66.00%,5.24,respectively.The phagocytic activity of leukocytes in group KM0.3,M0.3 were not significantly higher than the control group(P>0.05).The lysozyme activity,blood serum superoxide dismutase activity in group KM0.2 were significantly higher than the control group(P<0.05),LSZ reached to the top level on the 35th day,SOD reached to the top level on the 7th day,0.31,136.67,respectively.The blood serum superoxide dismutase activity in group KM0.3,M0.3 were not significantly higher than the control group.Fish fed diets with Kon-Mos supplementation had significantly higer viscera index,growth rate and lower feed conversion ratio.The growth rate of group KM0.2 was the highest(95.68%),and feed conversion ratio was the lowest(1.63).The group M0.3 had significantly higher growth rate and lower feed conversion ratio than the control group,64.91%,1.84,respectively.