Abstract: Objective：To investigate the role of microRNA-543 (miR-543)on chondrocytes in rat model of osteoarthritis and its biological mechanisms. Methods：The rat model of osteoarthritis was established and real-time PCR was used to detect the expression of miR-543. The expression of miR-543 was compared between osteoarthritis and normal rats. The chondrocytes of chronic osteoarthritis rats were isolated in vitro and then were transfected with miR-543 mimics. MTT assay was used to observe the effect of miR-543 overexpression on cell proliferation, and the expressions of apoptosis-related murine double minute 4 (MDM4), protein kinase B1 (PKB1/Akt1), B cell lymphoma/leukemia-2 (Bcl-2), tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) were detected by real-time PCR or Western blotting. Results：The expression of miR-543 in cartilage tissues was significantly lower in osteoarthritis rats than that in normal rats (P<0.05). IL-1β could significantly decrease the survival rate of chondrocytes, up-regulate the expression of MDM4, down-regulate the expressions of Akt1, Bcl-2, and increase the levels of TNF-α, IL-6(all P<0.05). While after miR-543 mimics was transfected, the survival rate of chondrocytes was significantly increased, the expression of MDM4 was significantly down-regulated, the expressions of Akt1, Bcl-2 were significantly up-regulated, and the levels of TNF-α, IL-6 were significantly suppressed (all P<0.05). Conclusions：The expression of miR-543 in cartilage tissue is significantly lower in osteoarthritis rats than that in normal rats. Up-regulated expression of miR-543 can antagonize IL-1β-induced chondrocyte injury by promoting chondrocytes proliferation, down-regulating MDM4 expression, up-regulating Akt1, Bcl-2 expression, and reducing the productions of inflammatory factors such as TNF-α and IL-6.