The total platelet count in normal human peripheral blood is 100-300,000/ml, and the clinical rule is that it is high if it exceeds 400,000/ml. In clinical practice, there are two types of high total platelet count: first, reactive hyperplasia; second, primary hyperplasia. Reactive hyperplasia is caused by other causes of elevated platelet count, commonly triggered by infection, major surgery, trauma and hemolysis. Primary hyperplasia is common in various myeloproliferative disorders, such as primary thrombocytosis, true erythrocytosis, early stage of myelofibrosis and accelerated stage of chronic granulocytic leukemia, etc. Therefore, there are multiple causes of elevated total platelet count, which require differential diagnosis. Patients with chronic granulocytic leukemia who have a significantly higher platelet count are often one of the signs of disease progression.