Abstract:The effects of different concentration of galacto-oligosaccharide on the intestinal development and microbiome structure of the newly weaned rats were explored.30 newly weaned rats were randomly divided into 5 groups：0%galacto-oligosaccharide group，5%galacto-oligosaccharide group，10%galacto-oligosaccharide group，10%fructo-oligofructose group，and AIN-93G normal diet group，and each group was fed with corresponding homozygous feed for 14 days.After the execution，the quality of liver and cecum organs was measured，the tissue of jejunum and cecum was fixed，and the contents of cecum were taken for 16S rDNA sequencing to determine the intestinal microbiome.The results indicated that there was no significant difference in the amount of food intake and weight gain of rats in each group.The cecal weight and volume increased significantly in the galacto-oligosaccharide addition group （p＜0.01），and the cecal villi height and villi height/crypt depth ratio increased significantly（p＜0.05）.10%galacto-oligosaccharide could effectively improve the proliferation of bifidobacteria and lactobacilli in the intestinal flora（p＜0.01）.The addition of high concentration of galacto-oligosaccharide could improve the intestinal absorption function of the newly weaned rats and promote the proliferation of probiotics.