Objective To explore the effects of Chinese herbal compound, Tengmei decoction, on type II collagen-induced arthritis (CIA) in rats, and to examine the changes of arthritis index (AI), limb swelling, joint tissue inflammatory infiltration, and the effects on immune-inflammatory factors. Methods Sprague-Dawley rat models of arthritis were successfully established by intradermal injection of type II collagen and Freund's complete adjuvant. The model rats were randomly divided into model group, positive drug group, and high- and low-dose Chinese medicine groups, 6 rats in each group. The intervention and treatment period was 12 weeks. To measure weekly the anteroposterior and transverse diameters of the rear ankles and wrists, the transverse diameter of the claw foot palm pad, the thickness and the highest point width of hind limb plantar joint swelling, and to evaluate the integrated scores of joints and limbs swelling using a vernier caliper. Results ① Compared with the normal group, the total arthritis scores and hind limbs AI scores of the model group were significantly increased (P<0.05 or P<0.01). The left forelimb AI scores were significantly increased during 10-12 weeks (P<0.05). The anteroposterior and transverse diameters of the left hind limb, the thickness of the highest point measurement of the left hind foot pad metatarsal were significantly increased (P<0.05 or P<0.01) in different time periods between 1-12 weeks. Compared with the model group, the total scores and the left hind limb joints AI scores of the high- and low-dose drug groups were decreased after 6 weeks (P<0.05). ② Compared with the normal control group, levels of mRNA transcription and protein expression of IL-6 and TNF-α were significantly up-regulated (P<0.01) in the model group. Compared with the model group, the levels of mRNA transcription and the expression of IL-6 and TNF-α proteins were significantly down-regulated in the positive group and Chinese medicine groups (P<0.01). ③ Histological examination showed that the low-dose TCM significantly improved the CIA synovial hyperplasia and inflammatory cell infiltration. Conclusions The molecular mechanism of Chinese herbal compound Tengmei decotion in improving joint pathological injury of CIA rat models may be related to its inhibitory effect on the high expression of immune-inflammatory factors in the synovial tissue of CIA rats.