Polyps are lesions that protrude or bulge from the mucosal surface of the intestinal cavity. With the help of colonoscopy, the size and number of polyps can be detected, but the most effective gold standard for the benignity and malignancy of polyps is to determine them by pathological biopsy. According to the pathological classification, polyps are divided into inflammatory polyps, hyperplastic polyps, dysplasia, adenomatous polyps and so on. Among them, adenomatous polyps are common, accounting for about 70%-80%, and the size is usually about 0.5-2 cm. Adenomatous polyps include tubular adenoma, villous adenoma, and villous tubular adenoma. Tubular adenomas are the most common histologic type of adenoma, accounting for 60-80% of adenomas and increasing with age. Most tubular adenomas exhibit mild atypical hyperplasia and have a low cancer rate of about 5%. The incidence of choriomeningeal adenoma is 1/10 of that of tubular adenoma, but the cancer rate is higher, generally 40%, so it is considered a cancerous lesion. Choroidal tubular adenoma is an adenoma that has both of these histological features, and its cancer rate is between that of tubular adenoma and choroidal adenoma. In addition to the pathological classification of adenomatous polyps, it is believed that the size and number of adenomas have a great influence on the likelihood of carcinoma. The cancer rate of adenomatous polyps less than 1 cm is almost zero, and the chance of cancer of adenomatous polyps larger than 1.0 cm increases, while the cancer rate of adenomatous polyps 1-2 cm is about 10%, and the cancer rate of adenomatous polyps >2 m is as high as 50%. According to the statistics, the cancer rate is 12%-29% for less than 3 polyps and 66.7% for equal or more than 3 polyps. In summary, adenomatous polyps are recognized as precancerous lesions of colorectal cancer in terms of their cancer rates in all aspects. That said, it does not mean that all adenomatous polyps are precancerous. Therefore, detection of adenomatous polyps need not be overly worrisome and the following practices can be followed to effectively avoid cancerous changes. After endoscopic removal of adenomatous polyps, follow-up colonoscopy should be performed within 3~6 months to ensure clean removal; residual polyps should be removed, while most patients who are still not removed after 2~3 more follow-up visits should be surgically removed; after complete removal, most patients should be examined once in 5 years.