OBJECTIVE To investigate the mechanism by which the traditional Chinese medicine formula Xibining Ⅱ modulates cold-stimulus pain sensitivity in rats with cold-damp obstruction-type knee osteoarthritis （KOA） based on the SET domain bifurcated histone lysine methyltransferase 2 （SETDB2）/histone H3 lysine 9 trimethylation （H3K9me3） signaling axis. METHODS Fifty SD rats were randomly divided into control group （intragastric administration and intrathecal injection of equal volumes of normal saline）， model group （intragastric administration and intrathecal injection of equal volumes of normal saline）， Xibining Ⅱ low- and high-dose groups （4， 8 g/kg Xibining Ⅱ， intragastric administration）， and high-dose of Xibining Ⅱ+small interfering RNA （siRNA） group （8 g/kg of Xibining Ⅱ via intragastric administration and intrathecal injection of SETDB2 siRNA at 0.2 mmol/L， 20 μL per rat）， with 10 rats in each group. Except for the control group， cold-damp obstruction-type KOA model was induced in other groups. Drug administration commenced 14 days post-modeling and continued for 28 days. Following the final administration， the following were assessed： behavioral changes in cold-stimulation pain sensitivity， histopathological changes in the articular cartilage of the knee joint， the contents of inflammatory factors [tumor necrosis factor-α （TNF-α）， interleukin-1β （IL-1β）] and pain mediators [calcitonin gene-related peptide （CGRP）， nerve growth factor （NGF）]， as well as the expressions of SETDB2/H3K9me3 signaling axis，inflammatory factors and pain mediators related proteins and mRNAs in dorsal root ganglion （DRG） tissue. RESULTS After 28 days of drug administration， compared with the model group， Xibining Ⅱ low- and high-dose groups exhibited significantly prolonged cold-stimulus paw withdrawal latency （P＜0.05）； the number of positive responses in the acetone low-temperature test was significantly reduced （P＜0.05）； Mankin score and the Osteoarthritis Research Society International score for knee joint tissue， as well as the levels of inflammatory factors and pain mediators in the serum and their expression in DRG tissue were all significantly decreased （P＜0.05）； the protein expressions of SETDB2 and H3K9me3 in DRG tissue were significantly increased （P＜0.05）. Intrathecal injection of SETDB2 siRNA reversed the above effects of high-dose of Xibining Ⅱ （P＜0.05）. CONCLUSIONS Xibining Ⅱ may alleviate inflammatory and pain responses by activating the SETDB2/H3K9me3 signaling axis， ultimately improving cold-stimulus pain sensitivity in rats with cold-damp obstruction-type KOA.