Objective: To investigate the incidence of BK virus (BKV) infection in renal transplanted recipients and analyze the risk factors of BKV infection. Methods: By measuring BKV DNA loads in urine and blood samples of the patients, 157 renal transplanted recipients who had received renal transplantation in our hospital from Dec. 2014 to Dec. 2015 were divided into 3 groups: BK viruria group, BK viremia group and normal group. Data of each group was then recorded, including age, gender, kidney primarydisease, type of dialysis, preoperative immune induction therapy，delayed recovery of graft function(DGF), HLA mismatch, acute rejection, dosage of postoperative corticosteroid, postoperative immunosuppressive regimen, postoperative pulmonary infection, et al. The risk factors of postoperative BKV infection were analyzed by logistic regression. Results: It was found that the incidence of BKV viruria was 35.03% (55 cases), that of BKV viremia was 11.46% (18 cases), and that of BKVAN was 0.63% (1 case). Univariate analysis by Logistic regression analysis found that postoperative immunosuppressive regimen (P=0.031) and postoperative hormone dose (P=0.037) were significantly related to BKV viruria. Multivariate analysis by Logistic regression analysis found that postoperative immunosuppressive regimen(P=0.041，OR=2.146) and postoperative hormone dose (P=0.042，OR=1.739) were significantly related to BKV viruria. Conclusion: Incidence of BKV viruria was higher than that of BKV viremia. There was only one recipient diagnosed BKVAN. Postoperative immunosuppressive regimen and postoperative hormone dose may be the risk factors of BKV viruria.