Galectin-9 (LGALS9) plays an important role in the occurrence and development of many diseases, including immunity, infection, cancer, etc. Studies have found that LGALS9 can phosphorylate ERK1/2 in the MAPK pathway. However, there is currently no clear conclusion on the role of LGALS9 in OA, and it is worth further exploring the regulatory role and mechanism of LGALS9 in OA in this study. In the initial stage, we collected 6 cases of hip joint soft tissue from normal individuals and 6 cases from OA patients clinically to analyze the differential expression of LGALS9 between normal individuals and OA patients; Subsequently, RNAi technology was used to preliminarily clarify the regulatory role of LGALS9 in an in vitro OA model; Then, lentivirus was used to knock down and overexpress LGALS9, and in vivo and in vitro OA models were constructed. QRT-PCR, western blot, safranin fast green staining (SO), immunofluorescence and other experimental methods were used to quantitatively analyze inflammatory and signaling pathway indicators, further improving the regulatory effect of LGALS9 on inflammation and the pathogenesis of OA.