Platelets, red blood cells and white blood cells are the three main cells of human blood, of which platelets are involved in blood clotting, and they cooperate with the clotting factors in the blood to help stop bleeding in time when blood vessels are injured. In general, the number of platelets in normal people is relatively stable, and under the influence of certain diseases the number of platelets can decrease to below the normal range, a condition we call thrombocytopenia. Thrombocytopenia is the most common cause of abnormal bleeding. Bleeding from the skin may be the earliest symptom. Purple pinpoint bleeding spots often appear on the lower extremities, minor injuries may also cause bruising, there may be bleeding from the gums, urine and stool, female patients may have increased menstruation, and surgery and trauma can be dangerous because the bleeding cannot be easily stopped. There are different severity levels according to the degree of platelet count reduction. If the platelet count is only mildly reduced ((50-100) × 10^9/L), the patient has no obvious bleeding manifestations; the platelet count is reduced to (30-50) × 10^9/L may show bleeding symptoms; the platelet count is reduced to (10-30) × 10^9/L may have obvious bleeding manifestations; when platelets below 10×10^9/L there is a risk of severe gastrointestinal bleeding or fatal intracranial hemorrhage. Thrombocytopenia is divided into secondary and primary, the former refers to thrombocytopenia due to other diseases such as liver disease, autoimmune disease, viral infection, malignant tumor and other diseases. Many patients visit the doctor because of thrombocytopenia, and the potential other diseases behind it are diagnosed in the process of perfecting the examination, gaining time for further treatment. Primary thrombocytopenia, on the other hand, is a hematologic disorder caused by disorders of the immune system that excludes the factors mentioned above. The condition can be prolonged and recurrent, severely affecting the patient’s quality of life and requiring professional, long-term treatment and follow-up.