Blood consists of red blood cells, white blood cells and platelets. The main function of red blood cells is to supply oxygen to tissue cells, the main function of white blood cells is immune defense function (anti-infection) and the main function of platelets is to stop bleeding. When leukemia occurs, leukemic cells destroy normal red blood cells, white blood cells and platelet-producing megakaryocytes, resulting in anemia, infection and bleeding. Common clinical manifestations include palpitations and shortness of breath, dizziness and weakness, fever, respiratory infections, perianal infections, intestinal infections, bleeding spots on the skin, bleeding gums, nasal bleeding and gastrointestinal bleeding. In addition, due to the massive proliferation of leukemia cells, patients can develop bone pain, soft tissue masses, enlarged lymph nodes, and enlarged liver and spleen. Therefore, when the above symptoms appear, you should think about the possibility of leukemia and go to the hospital promptly to check the blood routine and if necessary, bone marrow examination is needed.