Low macroplatelets refer to the low proportion of platelets with a diameter of 3μm to 20μm to all platelets. Normal platelet cytoplasm, which is round, oval or irregular in shape with a diameter of about 2~3μm, is medium-sized platelets, accounting for about 44.3%~49% of the total number of platelets. Platelets with a diameter of less than 2 μm were small platelets, accounting for about 33% to 47% of the total number of platelets. The diameter of large platelets is about 3μm~20μm, accounting for about 8%~16% of the total platelets, which is mainly seen in various myeloproliferative disorders, such as aplastic anemia and myelodysplastic syndromes, etc., in which the patients’ hematopoietic function is impaired, and their ability to produce megakaryocytes decreases, generating fewer platelets of larger size, causing the proportion of large platelets to be low. When the proportion of large platelets is low, it is recommended to consult a doctor in time to clarify the diagnosis and standardize the treatment under the guidance of a physician.