Rheumatoid arthritis calf belly pain is related to the damaged immune system, inflammatory stimulation, tissue swelling and other reasons. 1. Impaired immune system: because rheumatoid arthritis is an autoimmune disease, mainly characterized by erosive arthritis, and its pathological basis is characterized by synovial inflammation, so some patients will have symptoms of calf belly pain. 2. Inflammatory stimulation: pathogenic microbial infection is the main cause of rheumatoid arthritis, therefore, when the cartilage and bone tissue is stimulated by inflammation, calf pain will occur. 3. Tissue swelling: because the patient’s joint tissues will be swollen, easy to affect the blood circulation of the legs, in the long run, it is easy to occur neurological lesions, followed by calf pain, hyperalgesia, tendon reflex hyperactivity and other manifestations. It is recommended that patients with rheumatoid arthritis calf pain consult the rheumatology and immunology department in a timely manner, and actively cooperate with the doctor to improve the relevant examinations, to clarify the cause of the disease, standardized treatment, and strengthen the management of daily life, which can alleviate the discomfort and improve the quality of life.