Abstract:Objective To analyze the difference of intestinal flora between Tibetan patients and Han patients with irritable bowel syndrome (IBS) by 16S ribosomal deoxyribonucleic acid (rDNA) sequencing.Methods Twenty-five Tibetan patients (Tibetan group) and 20 Han patients (Han group) diagnosed with IBS from April 2018 to January 2019 were selected.16S rDNA sequence in feces was performed by Illumima Miseq in two groups,and the bioinformatics analysis was conducted on the sequencing results.Results Simpson index showed that the species diversity of intestinal flora in Tibetan IBS group were significantly lower than that in Han IBS group (P=0.030 6).Species difference analysis showed that the abundance of Bacteroidetes,Prevotella_9,and the colonization resistance B/F value of intestinal flora in Tibetan IBS group were significantly higher than those in Han IBS group (P=0.016 99,0.000 934 1,0.006 644,respectively),while the abundance of Bacteroides,Blautia and Escherichia-Shigella were significantly lower than those in Han IBS group (P=0.040 91,0.000 108 1 and 0.036 49,respectively).Phylogenetic Investigation of Communities by Reconstruction of Unobserved States（PICRUSt） function prediction analysis showed that there were no significant differences in cluster of orthologous groups of proteins(COG)function classification and Kyoto Encyclopedia of Genes and Genomes (KEGG) function prediction between two groups(P>0.05). Conclusion In Tibetan IBS patients,the intestinal flora imbalance is less serious, and the colonization resistance of intestinal flora is enhanced,with the decrease of pathogenic bacteria and increase of beneficial bacteria compared with Han patients. This conclusion can provide the individualized treatment of Tibetan IBS patients.