The most common type of leukemia in children is acute lymphoblastic leukemia. After children suffer from acute lymphoblastic leukemia, the abnormalities in blood routine include: first, the abnormalities in the number of leukocytes, generally the number of leukocytes is increased, which can reach the level of tens of thousands of leukocytes per milliliter, and at the same time, among peripheral leukocytes, the proportion of lymphocytes is obviously increased, and the proportion of neutrophils is decreased. Secondly, the change of blood routine is anemia, which is manifested in the decrease of the number of red blood cells and the decrease of hemoglobin concentration, but the morphology of red blood cells and the average hemoglobin amount of red blood cells are generally normal. Third, is the reduction of platelet count, platelet count can be mildly reduced, can be moderate or severe reduction, the more severe the reduction of platelet count, the child will show obvious bleeding symptoms, manifested as bleeding spots on the skin and mucous membranes, petechiae, and in severe cases, there will also be bleeding from the nose and gums.