Surgical site infection (SSI) is a challenging complication after intertrochanteric fracture surgery but without a large‐sample size study to investigate the incidence and risk factors of it. The present study was to investigate the incidence and risk factors of SSI after intertrochanteric fracture surgery. A total of 1941 patients underwent intertrochanteric fracture surgery between October 2014 and December 2018 were included. Demographic data, surgical variables, and preoperative laboratory indexes were obtained from a prospective database and reviewed by hospital records. The optimum cut‐off value for quantitative data was detected by receiver operating characteristic analysis. The univariate analysis and multivariable analysis were conducted to analyse the risk factors. In total, 25 patients (1.3%) developed SSI, including 22(1.1%) superficial infection and 3(0.2%) deep infection. After adjustment of multiple variables, gender (odds ratio[OR] 2.64, P = .024), time to surgery>4 days (OR 2.41, P = .046), implant (intramedullary or extramedullary devices) (OR 2.96, P = .036), ALB<35 g/L (OR 2.88, P = .031) remained significant factors. In conclusion, the incidence of SSI after intertrochanteric fractures surgery was 1.3%, with 1.1% for superficial and 0.2% for deep infection. Gender, time to surgery>4 days, the implant (intramedullary or extramedullary devices), and ALB<35 g/L were independent risk factors for the rate of SSI.