The volume of red blood cells in the peripheral blood of a healthy person is 80-100 fL; exceeding 100 fL is a high red blood cell volume. In clinical practice, the most common type of disease with high red blood cell volume is called megaloblastic anemia, which is common in elderly patients and is associated with folic acid and vitamin B12 deficiency. The most effective treatment for megaloblastic anemia is folic acid and vitamin B12 supplementation. By supplementing with folic acid and vitamin B12, the patient’s anemia symptoms will significantly improve and the red blood cell volume will gradually decrease to the normal range. At the same time, clinically high red blood cell volume is also seen in some patients with hemolytic anemia. For patients with hemolytic anemia, the preferred treatment is glucocorticoid supplementation, which can be taken with prednisone acetate and dexamethasone. In addition, along with hormone supplementation, folic acid can also be appropriately supplemented for better results.