Routine blood tests alone cannot be used directly to determine leukemia, but only play an auxiliary role, and need to be combined with bone marrow images and other values to determine and confirm the diagnosis. The indicators used in routine blood tests to assist in the diagnosis of leukemia mainly include white blood cells, hemoglobin and platelets, which are only used as reference data for the diagnosis of leukemia. Leukemia-related routine blood indicators 1, white blood cells: including neutrophils, lymphocytes, etc., commonly increased lymphocytes, neutrophils decreased; 2, hemoglobin: common blood signs for anemia, neonatal hemoglobin <145g/L; less than 6 years old children hemoglobin <110g/L; children over 6 years old hemoglobin <120g/L; 3, platelets: platelet reduction, such as platelet count <100×10^9/L. Bone marrow picture shows 1. Acute leukemia: most patients have significant proliferation of nucleated cells, mainly primitive cells, a few have hypoproliferative; 2. Chronic leukemia: significant or extremely active bone marrow proliferation, mainly granulocytes, significantly increased granulocyte-red ratio, significantly increased neutrophils, late juvenile and rod-shaped nuclei granulocytes, increased eosinophils and basophils. Megakaryocytes were normal or increased and decreased in the late stage. Clinical manifestations 1. fever: lack of normal leukocytes leads to defense dysfunction and causes fever from infection; 2. bleeding: most children can have varying degrees of bleeding, mainly from the nasal mucosa, mouth, gums, and in severe cases, internal organs and intracranial bleeding; 3. anemia: it is one of the common early symptoms of childhood leukemia, which usually worsens gradually, leading to pallor, dizziness, and weakness. Note that the diagnosis of leukemia cannot be confirmed by routine blood tests alone, and some leukemia can be better treated or even cured by medication, so parents do not need to be overly anxious about the abnormalities of a single indicator of blood routine.