Methotrexate is one of the important drugs for the treatment of childhood acute lymphoblastic leukemia. The genetic polymorphisms of methotrexate metabolizing enzymes and transporter are closely related to its effects and adverse reactions. Despite the improvement of chemotherapy regimens in recent years, the toxicity of methotrexate may still affect the quality of life of children, even life-threatening. Detecting gene polymorphisms of methotrexate metabolism-related enzyme and transporter gene in order to guide clinical treatment will increase the safety of treatment, provide a theoretical basis for clinical rational use of drugs and personalize treatment.