Objective To investigate the predictive significance of Septin9 gene methylation(mSEPT9)in peripheral blood in the diagnosis of colorectal adenoma.Methods A total of 52 subjects were included,31 patients with colorectal adenomas were collected as the experimental group in the Department of Pathology and 21 subjects with negative colonoscopy in the gastroenterology outpatient clinic were used as the control group from October 2020 to May 2022.mSEPT9 was detected in the two groups,and the results of CEA level in peripheral blood were collected.All the results were statistically analyzed using the Receiver Operating Characteristic(ROC).Results The area under the curve(area of the ROC:AUC)of mSEPT9detectionto predict the development of adenoma was 0.7205(P<0.05),And the cut-off value(CT value)was 39.55,the corresponding sensitivity was 90.91%and the specificity was 56.67%.The AUC of CEA detection for predicting adenoma was 0.5333(P>0.05).Conclusions The detection of mSEPT9 is better than that of CEA tumor marker detection in peripheral blood for screening colorectal adenomas with good sensitivity and relative specificity.Invasive colonoscopy for people with positive mSEPT9 screening results can be easier to accept by the general population.