Objective To study the pathology and its significance of early colorectal cancer and precancerous lesions treated by endoscopic submucosal dissection （ESD）. Methods A total of consecutive 113 cases were collected at the endoscopy center from August 2012 to June 2016， which were diagnosed as early colorectal cancer and precancerous lesions and undergone ESD. According to Japanese colorectal cancer treatment guidelines， specimens were processed and pathologically evaluated for histological type， tumor diameter， depth of invasion， budding grading， vessel invasion, and horizontal and vertical margin， as well as curative resection. Results There were 63 cases of adenoma （55.75％）, including 29（25.66％） tubular adenoma， 2（1.77％） villous adenoma， and 32（28.32％） villioustublar adenoma. Thirty-four cases of serrated lesion were found， which included 19（16.81％） traditional serrated adenoma， 11（9.73％） sessile serrated adenoma， and 4（3.54％） hyperplasic polyp. There were also 16（14.16％） cases of early colorectal cancer with 7 cases of well-differentiated adenocarcinoma， 7 cases of moderately-differentiated adenocarcinoma， 1 case of poorly-differentiated adenocarcinoma， and 1 case of mucinous adenocarcinoma. Vessel invasion were observed in 2 of 16 cases of early colorectal cancer which were both moderately-differentiated adenocarcinoma in sigmoid colon. The vertical margins were negative in 108（95.58％） of 113 cases. Positive vertical margin were found in only 1 case （moderately-differentiated adenocarcinoma，pT1b2） and another case was suspected as positive. The rest 3 cases could not be precisely diagnosed. The horizontal margins were negative in 80（70.80％） of 113 cases and positive horizontal margin were found in 20（17.7％） cases （19 adenoma and 1 moderately-differentiated adenocarcinoma）. Thirteen cases cannot be precisely diagnosed. Histologically， complete resection rate was 82.30％. The complete resection rate of invasive adenocarcinoma was 93.75％. Among 16 cases of invasive adenocarcinoma， 5 cases （curative rate： 31.25％） were judged as curative resection whereas 11 cases were considered as non-curative resection. Seven non-curative resection cases were treated with further surgery and did not relapse after the follow-up. Conclusion The standardized processing and precise histopathological evaluation are key factors for colorectal ESD technique， which play an important role in the success of endoscopic therapy.