The present experiment was conducted to study the effects of different levels of oligosaccharide(FOS) and complex CPP preparation(CPP) in diets on growth performance and serum biochemical parameters for weaned piglets. 240 crossbred DLY( Duroc× Landrace× Yorkshire) 21-day-old weaning piglets, about 7.2 kg in initial body weight were selected and randomly divided into 6 groups, with 2 repeats for each group, 20 each repeat(half male and half female.). Group 1, as the control group, fed base diet(BD) , group 2 fed BD adding 0.10% aureomycin, group 3, 4, 5, 6, respectively, fed BD adding 0.05% CPP, 0.05% FOS, 0.20% FOS and 0.10% FOS + 0.05% of CPP. Feeding trial was conducted for 35 days.Results: (1) Intestinal pH: Compared with the control group, the pH values of jejunum, ileum, cecum and colon in the 3, 4, 5 and 6 groups were significantly lower (P < 0.05), while there was no significant difference between the antibiotic group and the control group (P > 0.05).(2) Small intestinal villus morphology: Duodenal segment, villus length of 6 groups was significantly increased compared with the control group (P < 0.05), villus height to recess depth ratio (V/C) was significantly increased (P < 0.05). There was no significant difference in villus length between groups in jejunal segment (P > 0.05). Groups five V/C was significantly higher than that in the control group (P < 0.05). Compared with the control group and the antibiotic group, the ileal segment in the six groups significantly increased V/C (P < 0.05).(3) Intestinal flora Adding FOS, CPP and their combination could reduce the number of E. coli and Salmonella in different intestinal segments, and increase the number of Lactobacillus and Bifidobacteria. Among them, the effect of joint addition is the most obvious. Conclusion: Adding FOS and C PP to the diet of weaned piglets could effectively reduce the intestinal pH value of piglets, increase the length of intestinal villi and V/C, reduce the number of harmful bacteria and increase the number of beneficial bacteria. It is beneficial to maintain the balance of intestinal morphology and microflora and improve the intestinal health of piglets. Among them, the combination of 0.10% FOS and 0.05% CPP is the best, followed by 0.20% FOS.