Abstract: Objective To study the risk factors of postoperative blood transfusion in patients undergoing bilateral total knee arthroplasty(TKA). Methods One hundred and twenty-five patients(250 knees)who underwent bilateral TKA in our hospital from February to December in 2014 were divided into two groups: transfusion treatment group(n=49)and non transfusion treatment group(n=76), according to whether patients had undergone transfusion treatment or not after surgery.Risk factors related to the transfusion treatment were analyzed by single factor and logistic regression analysis. Results Single factor analysis showed that preoperative prothrombin time(PT, P=0.012), preoperative activated partial thromboplastin time(APTT, P=0.011), surgery time(P＜0.000 1), postoperative 1 d D-value Hb%(P＜0.000 1)were correlated with postoperative transfusion treatment significantly, multivariate logistic regression analysis showed that surgery time(OR: 1.094, 95% CI: 1.054-1.135, P=0.000), postoperative 1d D-value Hb%(OR: 1.122, 95% CI: 1.063-1.185, P=0.000), preoperative APTT(OR: 1.191, 95% CI: 1.042-1.362, P=0.010)were correlated with postoperative transfusion treatment significantly. Conclusion The preoperative APTT, surgery time and postoperative 1 d D-value Hb% of the patients with bilateral TKA are risk factors for postoperative transfusion treatment, timely assessment of these factors is preferred so as to prevent and reduce the occurrence of postoperative anemia.