Effects of dietary supplementation of fructooligosaccharide (FOS), raffinose (ROS), xyloligosaccharide (XOS) on intestinal flora, diarrhea index and fecal quality in tibetan mastiff puppies were evaluated in this study. Twelve tibetan mastiff puppies with the body weight of （10.18±1.66） kg were divided into four groups: control (basal diet), FOS (added with 0.3% FOS in basal diet), ROS (added with 0.3% ROS in basal diet), XOS (added with 0.3% XOS in basal diet).The faeces were collected on the day of 0, 21 and 42, and the fecal score, number of bacteria, diarrhea index, fecal ammonia, DM and pH were measured. The results showed that three oligosaccharides had the tendency to improve the fecal quality, the XOS group had significant effect on fecal quality on the day of 42 (P＜0.05). The count of total aerobic bacteria and Bacillus coli and the content of fecal ammonia in three oligosaccharide groups were significantly decreased (P＜0.05) and the count of Bacillus acidilactici in three oligosaccharide groups were significantly increased (P＜0.05) on the day of 42, respectively, and the FOS group had the best effect. Three oligosaccharides had the tendency to decrease the fecal pH. It was concluded that oligosaccharides could improve microflora balance, prevent diarrhea and improve fecal quality in some degree, and the FOS group had the most significant effect.［Chinese Journal of Animal Nutrition, ２００9，２1（5）:763-768］