Fecal DNA has a certain detection rate for bowel cancer, but there is a certain false positive rate, and it does not clinically confirm the diagnosis of bowel cancer. Positive result of fecal DNA test is only to consider the possibility of bowel cancer, and further colonoscopy is needed to confirm the diagnosis. Detection of bowel cancer by fecal DNA is a non-invasive test, which is basically harmless to patients, but the application of this test method in clinical practice needs to be supported by further large-scale clinical research data. For the clinical diagnosis of bowel cancer, the most important thing is invasive colonoscopy, which is by far the most accurate way to make the clinical diagnosis of bowel cancer through the biopsy specimen of suspicious tissues under the microscope and the pathological examination.