Heel blood is generally used in newborns to screen for phenylketonuria and hypothyroidism, and is not generally used to screen for leukemia, which is diagnosed on the basis of clinical presentation, blood counts, and bone marrow images obtained by bone marrow aspiration. The diagnosis of leukemia is usually based on clinical manifestations, blood counts and bone marrow picture obtained by bone marrow aspiration. 1. Clinical manifestations: anemia, bleeding, fever and infection, enlarged lymph nodes and splenomegaly. 2. Blood routine: abnormal levels of platelets, leukocytes, abnormal leukocyte ratio or count, and leukocyte classification of primitive and naive cells can be seen. 3. Bone marrow aspiration: the diagnosis can be confirmed by finding leukemia cells in the bone marrow picture. When leukemia is suspected, we should actively improve the examination, make a clear diagnosis, and choose a reasonable treatment plan according to different conditions under the guidance of doctors.