〔Abstract〕 Objective To evaluate the efficacy of endoscopic submucosal dissection in the treatment of lateral development tumors of the large intestine. Methods A total of 68 patients who underwent endoscopic surgery in Yangjiang People's Hospital from January 2018 to July 2022 were selected and randomly divided into two groups. 33 patients in the observation group underwent endoscopic submucosal dissection and 35 patients in the control group underwent endoscopic mucosal resection. The therapeutic effects of the two groups were compared. Results The operation time, hospital stay and intraoperative blood loss of the observation group were more than those of the control group, the difference were statistically significant (P < 0.05). The complete resection rate, the whole resection rate ≥ 3 cm and the whole resection rate of 1.5 ~ 3 cm in the observation group were higher than those in the control group, and the difference were statistically significant (P < 0.05). There were no significant difference in the total incidence of complications, recurrence rate and quality of life between the two groups (P > 0.05). Conclusion Endoscopic submucosal dissection for clinical treatment of patients with lateral development tumors of the large intestine can improve the diagnosis and treatment effect, the complete resection rate is higer.