ObjectiveTo investigate the occurrence and risk factors of surgical site infection (SSI) in patients with colon or rectal cancer.MethodsPatients who were diagnosed with colon or rectal cancer and underwent emergency or elective surgery in a hospital between January 1, 2008 and December 31, 2013 were monitored prospectively. General data, operation condition, and antimicrobial use of patients were analyzed, occurrence of SSI was observed every day and followed up after operation, risk factors of SSI were analyzed by univariate and multivariate analysis. ResultsA total of 694 patients with colon cancer(n=380) or rectal cancer(n=314) were monitored, SSI occurred in 125 patients, including 15 incisional infection and 110 organ/space infection, incidence of SSI was 18.01%；incidence of SSI in colon cancer patients and rectal cancer patients were 17.11% (65/380) and 19.11%（60/314）respectively. Univariate analysis showed that among colon cancer patients, incidence of SSI was higher in those with coinfection of other sites during perioperative period, underlying diseases, phase Ⅰcancer, and relaxation suture(all P<0.05); among rectal cancer patients, incidence of SSI was higher in those with coinfection of other sites during perioperative period, underlying diseases, obstruction, operation time>2 hours, stoma, drainage, relaxation suture, rinsing during operation, and use of antimicrobial agents>72 hours (all P<0.05); logistic regression analysis showed that the independent risk factors for SSI in colon cancer patients were underlying disease, coinfection of other sites during perioperative period, and relaxation suture(all P<0.05); independent risk factors for SSI in rectal cancer patients were underlying disease, coinfection of other sites during perioperative period, and stoma(all P<0.05). ConclusionPrevention and control measures should be taken according to risk factors of SSI in patients undergoing colon cancer and rectal cancer surgery, especially those who with chronic underlying diseases and other site infection during perioperative period; in addition, patients with colon or rectal cancer should also pay attention to relaxation suture and stoma respectively.