The blood component with hemostatic function is mainly platelets. Platelets are the smallest component of blood that can be stained, and the most important function is to participate in the processes of hemostasis, coagulation and fibrinolysis by initially stopping bleeding, participating in coagulation and promoting wound healing. Thrombocytosis is seen in primary and secondary thrombocytosis, etc., and thrombocytopenia is seen in aplastic anemia, megakaryocytic aplasia, thrombotic thrombocytopenic purpura, etc. 1. Initial hemostasis: after trauma to the body, through the adhesion between platelets and platelets, platelet thrombus is formed and adheres to the trauma, which can play a hemostatic role; 2. Participation in coagulation: platelets are involved in hemostasis through the formation of platelet factor Factor 3, promote the formation of thrombinogenase, adsorb and concentrate coagulation factors, activate or release a variety of coagulation factors, etc. to participate in the coagulation reaction and promote blood clotting; 3, promote wound healing: through the contraction of actin filaments, myosin filaments and other substances on platelets, platelets extend multiple pseudopods, and when the pseudopods contract and cause the serum to be squeezed out, it can make the blood clot contract, which is conducive to hemostasis and wound healing.