Objective To study the distribution of pathogens from infected surgical incision in colorectal cancer and its influence factor associated with incisional surgical site infection. Methods 280 patients after chemother-apy were involved in this study. The incisions of secretion were collected for bacterial culture to separate and identify pathogens. The suspicious factors such as age, gender，body mass index，diabetes and other complications and tumor stage were used to analysis the relationship between infection and these factors after chemotherapy. Results 67 cases of 280 patients were infected (23. 93% ) . 30 patients were infected after the first dose of chemotherapy, and the remaining 37 cases occurred within the first two times after chemotherapy. The infection mainly occurred in respiratory tract (36 cases) , gastrointestinal (11 cases) , urinary tract (10 cases) , skin and accessories (5 cases) , and other parts of body (5 cases) . Most of the infection pathogens were Gram-negative bacilli (70. 15% ) . The distribution of Escherichia coli with obesity and diabetes mellutus increased significantly ( P< 0. 05). The incidence of infection ( 26. 87% ) , Pseudomonas aeruginosa (14.93% ) were the highest. The incidences of SSI in patients was related to DUKES stage, BMI, diabetes , and operation type (P < 0. 05 ) , and there was little correlated with the age, gender and tumor type (P> 0. 05 ) . Conclusion Obesity, diabetes mellitus and tumor staging are the most important factors associated with SSI in colorectal cancer patients. Preventive measures for infections should be taken.