Objective: To systematically explore the intervention efficacy of annexin A5(AnxA5 on temporomandibular joint osteoarthritis (TMJOA) induced by complete Frend's adjuvant (CFA) in rats. Methods: Thirty-two 6-week-old male SD rats (weighing 200-250 g) were assigned to histological analysis (n=20) or micro-CT analysis (n=12). The TMJOA model was established by bilateral intra-articular injection of CFA, while the control group received saline. Three days later, TMJOA rats were randomly divided into three groups (n=8 each): CFA model group (saline injection), CFA+HA group [hyaluronic acid (HA), once weekly for 2 weeks], and CFA+AnxA5 group (AnxA5 injection every 3 days for 4 injections). The saline group was injected with the same frequency and dosage of saline as that of AnxA5. The changes in the structure of the temporomandibular joint were observed through HE and safranin O-eosin green staining, and the total thickness of the cartilage (TC), the thickness of the hypertrophic chondrocyte layer (HL), the thickness of the fibrocartilage layer (FL), as well as the thickness of the anterior band (A), Intermediate zone (In) and posterior bands (P) of the articular disc were measured.The changes in the content of glycosaminoglycans in the condylar cartilage matrix were observed by Alcian blue and toluidine blue staining. The contents of MMP 13, collagen Ⅱ and TNF-α in the condylar cartilage matrix were observed by Immunohistochemical staining. The infiltration quantity of M1-type macrophages was observed by immunofluorescence staining. The situation of subchondral bone remodeling of the condyle was observed by micro-CT, data such as bone volume fraction (BV/TV), trabecular number (Tb.N), and trabecular thickness (Tb.Th) were collected and calculated. Results: The results of HE and safinin-O fast green staining showed that compared with the thickness of each layer of cartilage and the thickness of the articular disc in the saline group [TC: (306.85±39.87) μm, HL: (123.16±27.19) μm, FL: (43.87±7.01) μm, A: (263.55±13.55) μm, In: (155.91±26.80) μm, P: (263.12±36.21) μm], the TC and HL in the CFA model group were significantly thinner [(218.30±38.32) and (79.90±18.54) μm ](P<0.001), FL was significantly thicker [(67.69±13.46) μm] (P<0.001), and the A, In and P of the articular disc were significantly thicker [respectively (305.27±23.37), (200.96±18.75) and (321.92±16.86) μm] (P<0.001)Compared with the CFA model group, the TC [(252.76±32.23) and (270.37±21.87) μm] and HL [(108.15±11.13) and (108.41±17.30) μm] in the CFA+HA treatment group and the CFA+AnxA5 intervention group were significantly thicker (P<0.05), while FL [(46.08±5.99) and (45.58±5.27) μm] was significantly thinner (P<0.01). The thickness of the A, In and P of the articular disc in the CFA+HA treatment group [(272.54±19.66), (180.24±14.47) and (273.79±29.28) μm] and in the CFA+AnxA5 intervention group [(263.66±10.68), (168.60±9.87) and (279.31±25.79) μm] were significantly thinner (P<0.05). The results of Alcian blue and toluidine blue staining showed that in the saline group, the staining of the condylar hypertrophic layer was obvious and uniform, while in the CFA model group, it was lightly stained, and in some areas, it was even unstained. After treatment with HA and AnxA5, the staining became relatively intense, and the loss of glycosaminoglycans slowed down.The IHC staining results showed that compared with the saline group (MMP13: 0.24±0.03,COL-Ⅱ:0.36±0.12), the content of MMP13 increased (0.37±0.07), and the content of COL-Ⅱ decreased (0.16±0.03) (both P<0.001). Compared with the CFA model group, the CFA+HA treatment group and the CFA+AnxA5 intervention group showed significantly decreased MMP13 levels (0.29±0.04 and 0.29±0.08) (both P<0.05) and significantly increased COL-Ⅱ levels (0.21±0.04 and 0.22±0.03, both P<0.01).The results of HE and IF staining showed that compared with the saline group, there was a large infiltration of inflammatory cells in the synovium of rats in the CFA model group and the number of M1-type macrophages increased (P<0.001). Compared with the CFA model group, both the CFA+HA treatment group and the CFA+AnxA5 intervention group showed a significant reduction in M1 macrophage numbers (P<0.05, P<0.01). The IHC staining results showed that compared with the saline group, the content of TNF-α in the CFA model group increased (P<0.001), while in the CFA+HA treatment group and CFA+AnxA5 intervention group, the content of TNF-α decreased (P<0.05;P<0.001).The Micro-CT results showed that compared with the saline group, the CFA model group exhibited significant decreases in condylar BV/TV, Tb.N, and Tb.Th (P<0.001, P<0.01, P<0.001).The difference between the CFA+HA treatment group and the CFA model group was not statistically significant. Compared with the CFA model group, the CFA+AnxA5 intervention group showed significantly higher BV/TV, Tb.N and Tb.Th (P<0.01, P<0.05, P<0.05). Conclusions: In the CFA-induced inflammation-dominated rat TMJOA model, AnxA5 can protect cartilage homeostasis, inhibit synovial inflammatory response, and simultaneously improve abnormal subchondral bone remodeling.