Cold snare polypectomy (CSP) has been shown to be safe and effective for the removal of polyps ≤10 mm in size， and is regarded as the ideal procedure for removal of small polyps. Hot snare techniques for diminutive polypectomy are still popular, but their use has decreased steadily in practice because of limited effectiveness and several drawbacks associated with the use of electrocautery,such as inadequate histologic interpretation and significant risk of complications. However, there have been few randomized controlled trials demonstrating complete resection rate by CSP or HSP for diminutive and small polyps. There are a paucity of data regarding which polypectomy technique is recommended according to polyp size and shape. The polypectomy techniques in the removal of small colorectal polyps in the 3-9 mm size range are not consistent. The study aimed at the direct comparison of the histologic polyp eradication rate of cold snare polypectomy (CSP) with that of hot snare polypectomy (HSP) in 3-9 mm sized flat or sessile colorectal polyps and the efficacy and safety of CSP to HSP in the removal of polyps 3-9 mm in size. In order to guide clinical practice.