A high platelet count means that the number of platelets in the peripheral blood is outside the normal range. Our country stipulates that the number of platelets in the peripheral blood of normal adults is 100,000-300,000 platelets per milliliter of blood, and exceeding 300,000 is an increased platelet count. There are two types of platelet count increase: reactive and primary. Reactive increase is caused by other causes of platelet increase, such as major trauma, surgery, infection, bleeding, etc., and can cause a reactive increase in platelet count, but after the risk factors are removed, the platelet count will gradually drop to the normal range. Primary increase in platelets is common in myeloproliferative disorders, such as primary thrombocytosis, true erythrocytosis, and chronic granulocytic leukemia, all of which can result in abnormally high platelet counts. In patients with chronic granulocytic leukemia, the presence of a progressive increase in platelet count often represents a progressive disease with a poor prognosis.