In the physiological state, the dynamic balance between the coagulation system, the anticoagulation system and the fibrinolytic system ensures the fluid state of the blood. Disruption of this dynamic balance under the action of certain pro-coagulant factors triggers the coagulation process, blood coagulation occurs in the blood vessels, and the solid mass formed in the state of blood flow in the living cardiovascular body is called thrombus. Thrombus formation conditions often include the following: 1, cardiovascular intima injury: is the most common factor in thrombosis, cardiovascular endothelial cells by a variety of factors and damage, promote coagulation factor activity, platelet activation, collagen exposure, local formation of persistent platelet adhesion pile, the formation of thrombus. Most commonly seen in arteritis, endophlebitis, myocardial infarction, hypertension, nicotine stimulation or surgical injury and other causes; 2. Altered blood flow status: platelets tend to adhere to the endothelium when blood flow is slow or flows through irregularly dilated or narrowed vascular lumen producing vortex; local coagulation active substances cannot be washed away by normal blood flow to accumulate locally; slow blood flow and severe hypoxia may touch coagulation function to form thrombus, and veins are more prone to thrombosis than arteries; 3. Increased blood coagulation: due to genetic factors as well as major surgery, trauma, extensive burns or pregnancy and childbirth, the number and activity of platelets and coagulation factors in the blood may increase, making the blood coagulation increase and easy to form thrombosis. In case of thrombosis, the treatment is mainly pharmacological, including thrombolytic drugs, antiplatelet drugs, anticoagulant drugs, and fibrin-lowering drugs. If the drug therapy is not effective, surgery can be used. It is recommended to treat the thrombus promptly after it is found to avoid the danger of aggravation.