Primary thrombocythemia with platelets 550×10⁹/L needs to be treated or not according to the specific condition. Regular observation, low-dose aspirin therapy and inhibition of cell proliferation therapy may be given depending on the severity of the condition, which may be mild, moderate or severe. 1. Observation: If the age is less than 40 years old and there are no risk factors for cardiovascular disease such as hypertension and diabetes, regular review and observation can be performed. 2. Small-dose aspirin therapy: If the age is between 40 and 60 years old, and there is no hypertension, diabetes, etc., you can use small-dose aspirin antiplatelet therapy, or clopidogrel, etc. if the side effects of taking aspirin are large or contraindicated. 3. Inhibition of cell proliferation therapy: if the age of 60 years old, have a history of thrombosis, or accompanied by hypertension, diabetes mellitus, etc. should be given hydroxyurea, interferon-alpha and other treatments. Primary thrombocythemia platelets 550 × 10⁹ / L whether the need for treatment, should be given by the doctor according to the actual situation of the disease to determine the use of medication should also be taken under the guidance of the doctor.