OBJECTIVE To investigate the risk factors of surgical site infection (SSI) in definitive surgery of intestinal fistulas. METHODS Patients with gastrointestinal fistula undergoing definitive operation during November 2011 to November 2013 in Jinling Hospital were prospectively enrolled in the study. Risk factors of SSI were analyzed. Patients' characteristics, surgery-related data and fistula-related data were prospectively collected. Risk factors of SSI were analyzed. RESULTS A total of 191 cases were enrolled and 51 cases developed SSI. Univariate analysis showed that patients with risk index category (RIC)≥2, length of abdominal incisions>15 cm, and duration of drainage tubes>10 days had significantly higher incidence of SSI (P<0.05). Multivariate Logistics analysis demonstrated that RIC and duration of drainage tube were independent risk factors for SSI (P=0.02, P=0.01, respectively). CONCLUSIONS RIC≥2 and duration of drainage tubes>10 days are independent risk factors for development of SSI.