Platelet hyperplasia means that the number of platelets in peripheral blood exceeds the normal range, and the clinical rule is that a platelet count of more than 400,000/mL in peripheral blood is platelet hyperplasia. There are two types of clinical platelet hyperplasia: the first is reactive hyperplasia, which is caused by other diseases, such as serious infections, trauma or major surgery, which may cause an increase in the number of platelets, such as craniotomy, where the number of platelets can increase significantly, sometimes reaching the level of 600,000/mL. The second in the clinical and myeloproliferative diseases, can also cause an increase in platelet count, the most common is primary thrombocytosis, true erythrocytosis, etc., the platelet count will appear abnormally high, often reaching the level of 1 million/mL, and in severe cases can even reach the level of 3 million/mL, the impact on the patient’s harm is huge, often need to apply hydroxyurea to reduce the platelet count or subcutaneous injection of interferon for treatment.