DMARD is a generic term for a group of drugs with disease-controlling effects but from different sources for the treatment of rheumatic diseases, some of which are immunosuppressive. The main drugs are methotrexate (MTX), salazosulfapyridine, hydroxychloroquine, leflunomide, gold agents, penicillamine, azathioprine, cyclophosphamide, cyclosporine, motilmic acid, thalidomide, etc. Methotrexate is a dihydrofolate reductase inhibitor that inhibits the metabolism of purines and pyrimidines and has the effect of reducing antigen-dependent T lymphocyte proliferation, increasing extracellular adenosine release, and promoting adenosine-mediated suppression of inflammatory responses. Methotrexate applied in small doses is important for preventing long-term complications and maintaining a stable state of the disease. Methotrexate has relatively rapid onset of action, effective inhibition of bone and joint destruction, few serious adverse effects, ease of administration and low price. Methotrexate is effective in the treatment of RA, and it can maximize the inhibition of synovial inflammation and prevent joint damage, and a small number of patients can achieve clinical remission with obvious joint protection. The main adverse effects of methotrexate are gastrointestinal reactions, abnormal liver function and interstitial lung changes, bone marrow suppression, etc. The occurrence of its adverse effects can be reduced with folic acid. The mechanism of action of salazosulfapyridine is to inhibit prostaglandin synthesis and reduce the activated lymphocytes in the blood circulation, resulting in a significant decrease in the titer of IgM-type rheumatoid factor. Adverse reactions include gastrointestinal reactions, liver function abnormalities and rash, and occasionally bone marrow suppression. Hydroxychloroquine mainly inhibits the presenting function of antigen-presenting cells and prevents the release of the inflammatory cytokine interleukin-21. The efficacy of hydroxychloroquine peaks 3-4 months after administration and should be replaced if it is still ineffective after six months of continuous use. Hydroxychloroquine can cause retinal degeneration, so the fundus should be checked every six months during the course of taking the drug. In addition, it is contraindicated in patients with sinus node insufficiency, bradycardia and conduction block. Leflunomide affects the synthesis of ribonucleic acid and deoxyribonucleic acid, and also inhibits the activity of T-lymphocyte protein tyrosine kinase, thus suppressing the immune response. Adverse reactions mainly include gastrointestinal reactions, such as diarrhea, etc. There may also be alopecia and rash, as well as increased liver enzymes and leukopenia and hypertension. Azathioprine interferes with adenine, guanine and ribonucleotide synthesis by inhibiting the synthesis of inosinic acid, and inhibits ribonucleic acid and deoxyribonucleic acid synthesis. It mainly acts on T lymphocytes and inhibits monocyte production and function, inhibits delayed hypersensitivity and immunoglobulin G (IgG) synthesis, and at higher doses also inhibits immunoglobulin M (IgM) synthesis, which increases the amount of complement and reduces rheumatoid factor production, and also has an anti-inflammatory effect, thereby relieving swelling and pain in rheumatoid arthritis joints, and has a therapeutic effect on preventing bone erosion or promoting bone erosion It has a therapeutic effect on preventing bone erosion or promoting bone erosion healing. It is often used in patients with systemic manifestations or complicated by connective tissue disease. Common side effects of azathioprine include nausea, vomiting, and occasionally pancreatitis and cholestatic hepatitis, usually within a few weeks of administration. Bone marrow suppression with leukopenia, thrombocytopenia, and anemia, especially granulocyte deficiency, are occasionally seen and are generally dose-related. Cyclophosphamide decreases the absolute number of T and B lymphocytes, more pronounced early on in B lymphocytes, significantly inhibits the transformation of lymphocytes into mother cells after stimulation with specific antigens, suppresses the antibody response to new antigens, and reduces immunoglobulin levels. Cyclophosphamide can improve the condition of rheumatoid arthritis, prevent bone erosion, and is effective in the treatment of rheumatoid vasculitis. The side effects of cyclophosphamide are large and commonly include nausea, vomiting, diarrhea, which are generally mild. 3-4 weeks after administration, it can cause hair loss, suppress the bone marrow and show a decrease in white blood cells, especially granulocytes, and platelets can also decrease. As the active metabolites of cyclophosphamide are mainly excreted in the urine, they have an irritating effect on the bladder mucosa, leading to hemorrhagic cystitis, in addition to xanthogranuloma, hypoprothrombin, ulcerative colitis, and renal tubular necrosis;; they can also cause menstrual irregularities, amenorrhea, and sperm reduction. In addition, cyclophosphamide can occasionally induce bladder cancer and is less commonly used in the treatment of rheumatoid arthritis due to the problem of long-term carcinogenesis and can be one of the combination options. The mechanism of morte-macrolate (MMF) is the selective inhibition of T and B lymphocytes associated with rejection. After 3 months of MMF administration, the number of affected joints decreased, joint function improved, rheumatoid factor in peripheral blood disappeared, and the total number of immunoglobulins and lymphocytes decreased to varying degrees. Adverse reactions were mainly focused on immunosuppression combined with infection. Cyclosporine is used in severe rheumatoid arthritis without myelosuppressive effects, and the main adverse effects are increased blood creatinine and blood pressure. Thalidomide is a glutamate derivative, which can effectively inhibit the expression of various inflammatory factors such as TNF-α and slow down the development of rheumatoid arthritis.