This is a prospective, randomized, open-label, non-inferiority, multiple-center trial. Outpatients who are scheduled to undergo colonoscopy and found eligible polyps will be randomized to receive either cold snare endoscopic mucosal resection (CS-EMR) or hot snare endoscopic mucosal resection (HS-EMR). This study aims to compare the efficacy and safety of CS-EMR or HS-EMR for the resection of non-pedunculated colorectal polyps sized 10-19mm.

Inclusion Criteria:

• 18-80 years of age;
• undergo colonoscopy in the Digestive Endoscopy Center of Peking Union Medical College Hospital, Beijing Tsinghua Changgung Hospital or Seventh Medical Center, General Hospital of the Chinese People's Liberation Army;
• volunteer to participate in this study and sign informed consent;
• at least one polyp sized 10-19 mm (Paris classification Is or IIa) by colonoscopy.

Exclusion Criteria:

• American Society of Anesthesiologists (ASA) status class 3 or above;
• poor bowel preparation (Boston bowel preparation scale < 6 points);
• known or endoscopic features indicating the submucous infiltration or malignancy;
• oral anti-coagulants, or antiplatelet agents, or known blood coagulation disorders, or bleeding tendency (platelets<50000 cells/mm3 or INR>1.5);
• a history of colorectal resection;
• emergency colonoscopy (hemodynamic instability and/or continued active gastrointestinal bleeding and/or requiring intensive care patients);
• inflammatory bowel disease, familial polyposis, and colorectal cancer;
• pregnancy or lactation;
• severe cardiopulmonary dysfunction, liver cirrhosis, chronic kidney disease, other malignant tumors, or severe infectious diseases.