Abstract: OBJECTIVE To analyze the diagnostic value of soluble myeloid cell trigger receptor-1 (sTREM-1), type II collagen C-terminal peptide (CTX-Ⅱ) and erythrocyte sedimentation rate (ESR) in suppurative infection of knee arthritis. METHODS A total of 106 patients with knee arthritis admitted to Hongze District People's Hospital of Huai an City in Jiangsu Province from Jul 2019 to Aug 2022 were enrolled as the knee arthritis group, and 112 healthy subjects under physical examination during the same period were in the healthy control group. Clinical data, serum sTREM-1, CTX-Ⅱ and ESR levels between the two groups were analyzed. Patients with knee arthritis were divided into the suppurative infection group (44 cases) and non-suppurative infection group (62 cases) according to whether suppurative infection occurred. Serum levels of sTREM-1, CTX-Ⅱ and ESR were compared between the two groups. Receiver operating characteristic curve (ROC) curve was used to analyze the individual and combined predictive value of serum sTREM-1, CTX-Ⅱ and ESR in suppurative infection in patients with knee arthritis. RESULTS The levels of serum sTREM-1, CTX-Ⅱ and ESR in the knee arthritis group were higher than those in the healthy control group (P＜0.05). The levels of sTREM-1, CTX-Ⅱ and ESR in the suppurative infection group were higher than those in the non-suppurative infection group (P＜0.05). The area under the curve (AUC) of the combined detection of serum sTREM-1, CTX-Ⅱ and ESR in the diagnosis of suppurative infection in patients with knee arthritis was higher than that of the three tests individual (P＜0.05). The sensitivity of serum sTREM-1, ESR and combination to predict suppurative infection in patients with knee arthritis was higher than that of CTX-Ⅱ; and that of ESR was higher than that of the combined detection (P＜0.05). The specificity of serum sTREM-1, CTX-Ⅱ and combined in the diagnosis of suppurative infection in knee arthritis patients was higher than that of ESR; and that of the combination of CTX-Ⅱ and sTREM-1 was higher than that of STREM-1 (P＜0.05). CONCLUSION The occurrence of suppurative infection in patients with knee arthritis can cause variation levels of sTREM-1, CTX-Ⅱ and ESR, and the combined detection of the three indexes has good predictive value for suppurative infection in patients with knee arthritis, and it is expected to become a marker for predicting suppurative infection in patients with knee arthritis.