Acute hemolytic anemia refers to acute hemolytic diseases that occur under the effect of certain triggers on the basis of pre-existing hemolytic diseases, and is commonly caused by blood transfusion of incompatible blood types, autoimmune hemolytic anemia, paroxysmal sleep hemoglobinuria, and pharmacological hemolysis. In addition, the presence of long-term infection, trauma, surgery, stress, pregnancy, drug-related factors or alcohol consumption can easily trigger acute hemolytic anemia. In severe cases, hemolytic crisis may occur, manifested as back pain, chills, high fever, decreased blood pressure, obvious bleeding tendency and coagulation dysfunction. Some patients will also develop splenomegaly, liver function impairment, and acute renal failure. In the ancillary tests, there will be a significant decrease in hemoglobin, an increase in reticulocyte count, and nucleated red blood cells and red blood cell fragments can be observed in peripheral blood smears. In the hematological examination, total bilirubin, especially indirect bilirubin, may be elevated, as well as plasma free hemoglobin, hemoglobinuria, and iron-containing hemoglobinuria. After the occurrence of acute hemolytic anemia, it is necessary to actively search for the cause of the disease and promptly remove the causative factors and causes of the anemia. In the treatment, glucocorticoids, gammaglobulin, immunosuppressants, and plasma replacement therapy can be considered if necessary.