Abstract: Objective To compare the different of bacterial community structure in the intestinal ecosystem of normal subjects with patients with colorectal carcinoma or polyps,and explore the effects of gut microbiota on the occurrence and development of colorectal cancer and precancerous lesions. Methods DNA samples were collected from the stool of volunteers undergoing colonoscopy.The participants were assigned into healthy group,polyps group and colorectal adenocarcinoma group according the colonoscopy.Taking high blood pressure as an independent factor,the participants of both healthy group and polyps group were assigned into hypertension subgroups and non-hypertension subgroups.DNA was prepared for PCR amplification of 16S rRNA genes and its V3-V4 regions.Then the DGGE was used to pre-evaluate DNA quality.The species and abundance of bacteria in each sample were analyzed by high-throughput sequencing.The differences of bacterial diversity and community structure of different groups were analyzed by principal component analysis. Results The intestinal bacteria among these groups had higher diversity.Based on the obtained operational taxonomic units(OTUs),Firmicutes(44.9%),Bacteroidetes(28.4%),Proteobacteria(18.6%) and Fusobacteria(5.5%) accounted for 97.4% of total OTUs,and made up the predominant bacteria in most samples,but the composition of the dominant bacteria in different samples was significantly different.The diversity index of each group showed no significant difference among different groups.The bacterial community structure of intestinal bacteria in healthy people was significantly different from that in cancer patients.The intestinal bacterial community structure of colon polyp was significantly different from the intestinal bacterial community structure of healthy people.There was no significant difference in the bacterial community structure between the non-hypertensive and hypertensive groups from the healthy group.There was no significant difference in colonic structure between the non-hypertensive and hypertensive groups. Conclusion The changes of intestinal microflora may affect or lead to the occurrence and development of colonic polyp and colonic tumors.It is helpful to study the microenvironment and mechanism of colonic cancer development,and the effect of hypertension on intestinal microflora of healthy people and intestine has no significant difference.