Objective To investigate the influencing factors of peripheral infections of knee joint tumor prosthesis as well as the value of serum D-D and TLR2 in predicting the infection risks so as to provide a reference for early diagnosis of tumorous periprosthetic infection(PJI)of knee joint.Methods The patients who were treated and followed up in our department from January 2008 to June 2020 were selected.According to the inclusion and exclusion criteria,136 of the patients were selected.The data including age,gender,BMI,history of diabetes,smoking history,tumor location,stage of malignant tumor,operation time,osteotomy length,intraoperative bleed-ing,and the percentage of neutrophils,leukocytes,serum D-dimer,and serum TLR value 3 days after operation were collected.The risk factors of PJI and the diagnostic value of serum D-dimer and serum TLR were analyzed.Results The incidence of PJI was 11.76%.Postoperative chemotherapy and operation time≥180 min were the risk factors of PJI(P<0.05).The area under curve(AUC)of the combination of two indicators,serum D-dimer and serum TLR2 were 0.917,0.894 and 0.778,respectively.The AUC of TLR2 was lower than that of the combina-tion of two indicators(P<0.05);The sensitivity was 0.975,0.908 and 0.708,respectively,and the specificity was 0.75,0.75,and 0.812,respectively.Conclusion Postoperative chemotherapy and operation time≥180 min are the risk factors of PJI.The combination of D-dimer and TLR2 has good diagnostic value.