1, rheumatoid factor: for the diagnosis has a relatively important reference value. But negative rheumatoid factor can not exclude the possibility of the disease, must be combined with clinical. 2, blood routine: rheumatoid arthritis patients may be accompanied by anemia, white blood cell count is mostly normal, in the active phase can be slightly increased. Anemia and thrombocytosis are associated with the activity of the disease. The erythrocyte sedimentation rate is often increased in most cases in active lesions and can be an indicator of disease activity. Serum iron and iron-binding protein levels are often decreased. 3. Complement and immune complexes: Total complement, C3 and C4 levels are mostly normal or even slightly elevated in patients with inactive arthritis. However, in patients with more extra-articular manifestations, there may be a decrease in total complement, C3 and C4 levels. C-reactive protein and sedimentation: C-reactive protein is closely related to activity index, morning stiffness, grip strength, joint pain and swelling, blood sedimentation and hemoglobin level, which decreases when the disease is in remission and increases when it is not. The C-reactive protein level does not increase when the disease is active. 5, synovitis examination: rheumatoid arthritis patients are generally inflammatory features of the synovial fluid, the total number of white blood cells up to 1.0 × 109 / L, or even more, protein > 40g / L, hyaluronidase < 1g / L, synovial fluid can be measured rheumatoid factor, anti-collagen antibodies and immune complexes. 6, X-ray examination: early X first can see the affected joint surrounding soft tissue swelling, late for joint subluxation, deformity and ankylosis.