More than half of patients with acute leukemia present with fever as an early symptom, which can be low-grade or as high as 39~40°C or even higher. At the same time, some patients may experience fatigue due to anemia, but the presence of low-grade fever and fatigue does not necessarily indicate leukemia. If leukemia is suspected, further tests such as a complete blood count and peripheral blood smear examination are necessary. If the patient has abnormal white blood cells, combined with anemia and a reduction in platelets, and a large number of blast or early immature granulocytes are seen on the peripheral blood smear, leukemia should be highly suspected, and a further bone marrow biopsy examination is needed for a clear diagnosis. If the complete blood count and peripheral blood smear show no significant abnormalities, leukemia can generally be ruled out.