Infection is an important cause of early death in patients with acute leukemia, and exploring how to reduce infectious complications during intensive chemotherapy for acute leukemia is of great theoretical and practical significances. Studies have shown that the intestinal flora of leukemia patients undergoes significant changes in the process of receiving treatment, and the changes in the intestinal flora of acute leukemia patients are closely related to the occurrence of infectious complications after chemotherapy. This article reviews the characteristics of intestinal flora, the relationship between intestinal flora and infectious complications, and the methods to restore the diversity of intestinal flora in acute leukemia patients.