Objective:To explore the clinical effect of endoscopic mucosal resection(EMR)and endoscopic submucosal dissec-tion(ESD)in the treatment of early colorectal cancer and precancerous lesions and its influence on postoperative complications.Meth-ods:Clinical data of 92 patients with early colorectal cancer and precancerous lesions were retrospectively analyzed.According to differ-ent treatment methods,the patients were divided into EMR group and ESD group.Propensity score matching method was applied to elim-inate the confusion bias caused by baseline data differences.Finally,41 pairs of patients with comparable baseline data were obtained from each group.The surgical time,postoperative hospital stay,lesion resection rate(en bloc resection rate,complete resection rate)and postoperative complications,inflammatory response indicators[C-reactive protein(CRP),white blood cell(WBC),interleukin-6(IL-6)]before surgery and at 24 hours after surgery,levels of tumor markers[carcinoembryonic antigen(CEA),carbohydrate antigen 199(CA199),carbohydrate antigen 242(CA242)]and fecal occult blood test before surgery and at 3 months after surgery and postop-erative recurrence,metastasis and survival after 1 year of follow-up were compared between both groups.Results:The surgical time and en bloc resection rate in ESD group were longer or higher than those in EMR group(P＜0.05).The incidence rates of complications were higher in ESD group than those in EMR group(P＜0.05).At 24 hours after surgery,the levels of CRP,WBC and IL-6 in both groups were increased(P＜0.05),but the levels in ESD group at 24 hours after surgery were lower than those in EMR group(P＜0.05).The tumor markers levels and fecal occult blood test were declined in both groups at 3 months after surgery(P＜0.05).After 1 year of follow-up,the total incidence rate of postoperative local recurrence or distant metastasis was 9.76％in ESD group and 2.44％in EMR group(P＞0.05).There was no difference in progression-free survival between the two groups at 12 months after surgery(log rank x2=1.924,P=0.165).Conclusion:The overall effect of ESD and EMR is similar in the treatment of early colorectal cancer and precancerous lesions,and ESD has higher lesion en bloc resection rate and lower recurrence risk,and there is a certain risk of complica-tions and it is necessary to select the appropriate method according to the patient's situation.