Myelodysplastic syndrome (MDS) accounts for a significantly higher proportion of hematology visits in recent years, but it is currently a difficult problem, both in terms of diagnosis and treatment options. Diagnosis is difficult, mainly in the determination of typing and prognosis. Traditionally, MDS is divided into five subtypes, but with the increasing understanding of MDS, the classification of MDS is also changing. According to the 2008 WHO staging, MDS has been divided into seven types. The combination of routine blood, bone marrow cell morphology, immunophenotyping, and cytogenetic techniques is the basis for its classification. Diagnosis and typing made only on the basis of bone marrow aspiration results without a systematic and comprehensive examination is inaccurate and cannot help in the choice of treatment plan, or even has the opposite effect. This is why it is important to emphasize that patients suspected of having MDS must undergo a comprehensive examination. In many hospitals, however, the tests are not complete, or they cannot or will not do immunophenotyping (no flow cytometry), or they cannot do chromosomal analysis, or they cannot do FISH, which is detrimental to the patient from this point of view. Treatment is difficult because the treatment is different for different types of MDS and should be individualized and disease-specific and not generalized. For example, for high-risk patients it is currently advocated to give treatment with a treatment plan similar to leukemia, such as patients with a primitive cell ratio of more than 10%, RCMD with severe hematocrit, young patients, etc., and even transplantation can be considered. And for low-risk but transfusion-dependent patients, emphasis is placed on giving supportive therapy. This year, two new drugs, azelastine (Dacor) and decitabine, have brought new hope to the treatment of MDS, with significantly higher remission rate and efficiency, and are currently the most effective drugs for the treatment of MDS. However, unfortunately, both drugs are expensive, costing about $300,000 to complete treatment, and are not treatments that can be applied to most people. Since 2006, we have carried out arsenious acid treatment for transfusion-dependent MDS patients one after another, treating 10 patients with good results. long-term transfusion of MDS brings many adverse effects, most notably a decrease in the patient’s quality of life and hemochromatosis. In such patients its application of intense treatment is not appropriate, one reason being the poor efficacy and the other being that the risks of intense chemotherapy offset the possible benefits. Arsenite, on the other hand, is milder, generally does not cause serious side effects, and the cost of treatment is affordable for most patients, making it a more desirable treatment option. Some of our patients who have been transfusion-dependent for a long time have had significantly fewer transfusions, significantly longer intervals between transfusions, and even up to more than a year without transfusions, and significantly higher hematocrit after 2-6 courses of arsenite application. For low-risk, long-term transfusion-dependent patients, the application of arsenious acid can be tried.