Objective：To establish the model of temporomandibular joint osteoarthritis（TMJ-OA） in rats induced by unilateral occlusal trauma，and to evaluate the histopathological changes of the condylar cartilage. Methods：The rats were randomly divided into two groups，the control group and the experimental group，and each group was divided into four subgroups（4，8，12 ，16 weeks group，6 rats in each group）. Metal-wire was attached to the right maxillary first molar by rein and the occlusion was elevated by 0.5 mm. The weight was recorded in 1，2，3，4，8，12，16 weeks after the operation. The rats were sacrificed at 4，8，12，16 weeks after occlusal trau－ma，respectively. The histopathological changes of condylar cartilage were evaluated by HE and safranin-O fast green staining，and the change of cartilage thickness was measured and analyzed. Results：①At the early stage of the operation，occlusal trauma had a great influence on the weight（t1=4.757，P1=0.000；t2=3.096，P2=0.003）. ②At the 8th week，the condylar cartilage of the experimental side showed obvious lesion of OA（Mankin score=8.67±1.37，t=-7.267，P=0.000）. There were horizontal fissures in fibrous cartilage. The chondrocytes were arranged irregularly in proliferating layer and showed the OA-like lesions. ③The histopathological damage caused by occlusal trauma to condylar cartilage was time-related. Conclusion：Model of TMJ-OA is successfully established in rats by unilateral occlusal trauma and the obvious pathologicalchanges are detected at 8 weeks. This could be a promising model for the study of the pathogenesisof TMJ-OA.