Background: Total knee arthroplasty (TKA) may be associated with serious complications that adversely affect outcomes and increase the likelihood of disability. However, few studies with sufficient sample size have reported postoperative complications following TKAamong Chinese patients. This study aimed to evaluate complications of TKA within 30 postoperative days and to identify the related risk factors. Methods: A retrospective complication?based analysis of TKA using the arthroplasty registry between 2008 and 2013 was performed by summarizing complications of TKA within 30 postoperative days. Multivariate logistic regression was used to identify the predicting factors for complications 30 days after operation. Results: A total of 1542 patients underwent 2254 primary TKA between January 2008 and December 2013. A total of 137 complications occurred within 30 days after operation with an incidence rate of 6.1%.The incidence rate of major systemic complications within postoperative 30 days was 2.3%, with cardiovascular and respiratory complications as the most common complications. The incidence rates of deep venous thrombosis (DVT) and local complications were 2.4% and 1.0%, respectively. The 30?day postoperative mortality rate was 0.1% (3/2254). Multivariate logistic regression analyses identified body mass index (BMI) of ≥30.0 kg/m2 (odds ratio [OR]: 1.47) and age ≥80 years (OR:1.87) as significant risk factors for postoperative systemic complications. A BMI of ≥30.0 kg/m2 was a significant risk factor for DVT (OR:2.86) and other complications (OR: 2.11). The comorbidity of diabetes was a risk factor for postoperative mortality (OR: 19.20). Conclusions: This study highlighted complications with cardiac and respiratory origins as the most common complications within 30 postoperative days following primary TKA. The BMI of ≥30.0 kg/m2 and age ≥80 years were significant risk factors for 30?day postoperative complications.