It is not uncommon for leukemia-like reactions to occur clinically, but because their clinical manifestations are not very specific, and the patients themselves have primary diseases, the clinical situation is more complex, and they are easily confused with leukemia and cause misdiagnosis. Therefore, for suspicious cases, we should actively search for the cause of the disease and consider it together with the results of all laboratory tests to avoid misdiagnosis and missed diagnosis and treatment. Leukemia-like reactions are distinguished from leukemia mainly in the following aspects: 1. Leukemia-like reactions have a clear etiology, such as severe infection, malignancy, hemorrhage, acute hemolysis, anaphylaxis and other primary diseases, and a history of poisoning or drug use. 2.The majority of leukemia-like reactions only have changes in blood picture, rarely have obvious abnormalities in bone marrow picture, and the blood picture is limited to the leukocyte series (except for those caused by blood loss and hemolysis), generally does not affect the red blood cell series and megakaryocyte series, and there is usually no clinical anemia and thrombocytopenia. 3. Leukemia-like reactions generally do not involve enlarged liver and spleen lymph nodes. In conclusion, leukemia-like reaction is a temporary abnormal reaction to the occurrence of white blood cell count and quality, which itself does not require special treatment, and with the cure and improvement of the primary disease, the blood picture can return to normal or improve, and the prognosis is better than that of leukemia.