Objective To investigate the risk factors of perioperative red blood cells transfusion for coronary artery bypass grafting (CABG) surgery. Method We retrospectively analyzed the clinical data of 534 patients underwent CABG in our hospital from January to March 2014 year. Those patients were divided into two groups:an on-pump coronary artery bypass grafting group (on-pump group) and an off-pump coronary artery bypass grafting group (off-pump group). There were 185 males and 54 females with a mean age of 59.1±9.4 years in the on-pump group. There were 233 males and 62 females with a mean age of 60.3±8.5 years in the off-pump group. Preoperative data, the relative parameters of extracorporeal circulation, the quantity of red blood cells transfusion of those two groups were compared. risk factors associated with red blood cells transfusion were evaluated by multivariate logistic regression analysis. Results The risk factors of perioperative red blood cells transfusion were age (OR=1.04, 95% CI 1.02-1.07, P=0.001) , weight (OR=0.95, 95% CI 0.93-0.97, P<0.001) , smoking (OR=0.61, 95% CI 0.39-0.94, P=0.027) , preoperative level of HCT (OR=0.90, 95% CI 0.85-0.96, P=0.001) and cardiopulmonary bypass (CPB) (OR=4.90, 95% CI 3.11-7.71, P<0.001) . During CPB, the nadir hemoglobin (nHb) (OR=0.63, 95% CI 0.47-0.84, P=0.002) was the only independent risk factor of red blood cell transfusion. Conclusions Age, weight, non-smoking, preoperative level of HCT, CPB are the risk factors for patients underwent CABG perioperatively and the lowest level of Hb in CPB is an independent risk factor of perioperative red blood cells transfusion.