Platelets more than 600 should actively deal with the cause, actively treat the primary disease. The normal range of platelets is (100~300)*10^9/L, and platelets >600*10^9/L are considered high platelets. The causes of thrombocytosis include reactive increase and pathologic increase. For reactive thrombocytosis, it is necessary to deal with the cause, such as actively stopping bleeding if it is caused by acute blood loss, actively combating infection if it is caused by acute infection, observing the change of condition or treating the original disease if it is caused by post-splenectomy or certain cancer patients. For those with pathologic increase, active treatment of the primary disease is needed, such as true erythrocytosis, chronic granulocytic leukemia and so on. When thrombocytosis occurs, it is important to treat it aggressively to avoid adverse events such as thromboembolism.