Currently, the exact cause of leukemia is not yet clear, but a large number of scientific studies have shown that radiation, certain chemicals, viruses and genetic factors may induce leukemia. Radiation such as γ-ray, X-ray, and other radioactive substances emitted invisible rays, people once or many times a small amount of exposure to radiation can cause leukemia. Here should indicate to the hospital to film, perspective, the radiation dose is very small and will not lead to leukemia. Many harmful chemicals on the hematopoietic system, and some can be induced leukemia. Here are some of the more certain chemicals and drugs, such as benzene and its derivatives, gasoline, paint, hair dye (aniline) etc.; drugs cause disease, such as chloramphenicol, phenylbutazone, some treat cancer alkylating agents can cause leukemia. Virus can guide hair leukemia has been recognized, such as human T lymphocytes pass the virus (Ⅰ and Ⅱ) can lead to leukemia, have been infected with this virus, not immediately leukemia, only when the presence of a number of risk factors in order to promote the hair of the disease, these risk factors, radiation, chemicals and certain drugs, many contacts with a large number of viruses, immune function and reduce the patient’s age, etc. are dangerous “catalytic" factor. Illness can be hereditary and genetic factors in the etiology of leukemia related to “genetic" does not mean parents to their children, and leukemia incidence of abnormal chromosomes and genes is significantly higher than normal. PH, the presence of chromosome is very relevant to the pathogenesis of chronic myelogenous leukemia. Twins, a person suffering from leukemia another person to the risk of very substantial.