Abstract:[Objective] To search the factors related to social frailty (SF) in elderly patients with knee osteoarthritis (KOA). [Methods] A total of 202 patients with KOA who visited the orthopedic outpatient department of our hospitals from March 2024 to March 2025 were enrolled into this study. The patients were divided into the non-SF group and the SF group according to the HALFT scale. Univariate comparison and binary multivariate logistic regression analysis were used to explore the risk factors of SF. [Results] Among the 202 patients, 75 had no SF with HALFT score of 0, accounting for 37.1%, whereas 67 in the early stage of SF with HALFT score from 1 to 2 points, accounting for 33.2%; 60 in the SF stage with HALFT score from 3 to 5, accounting for 29.7%. Regarding univariate comparison, the SF group proved significantly greater than the non-SF group in terms of age [(72.2±6.3) years vs (67.8±5.8) years, P<0.001], Kellgren-Lawrence (KL) scale [I/II/III/IV, (7/46/48/26) vs (19/31/20/5), P<0.001], and living style [living alone/with others, (2/73) vs (21/106), P=0.010], score of yielding coping style [(13.7±2.3) vs (11.4±2.1), P<0.001], avoidance coping style sore [(18.8±2.7) vs (16.5±2.8), P<0.001]. However, the SF group was significantly less than the non-SF group in terms of the exercise frequency [never/occasionally/often, (50/52/25) vs (30/19/26), P= 0.006], two-way social support score [(38.1±7.7) vs (44.7±7.0), P<0.001], positive psychological capital score [(101.7±19.1) vs (119.6± 20.7), P<0.001] and coping style score [(19.0±3.6) vs (22.4±4.3), P<0.001]. As results of binary multivariate logistic regression analysis, living with others (OR=0.105, P<0.05), higher two- way social support score (OR=0.881, P<0.05), and high positive psychological capital score (OR=0.952, P<0.05) were protective factors for the SF in elderly with KOA. However, advanced age (OR=1.104, P<0.05), advanced K-L stage (OR=7.685, P<0.05), and high yielding coping style score (OR=1.398, P<0.05) were the risk factors for SF. [Conclusion] The patients with advanced age, living alone, higher KOA stage, lower social support, lower psychological capital, and yield coping have a higher risk of developing SF. Clinically, targeted intervention measures should be taken to reduce the SF level of elderly with KOA.