I. Basic treatment: including bed braking, elevating the affected limb, prohibiting massage and pressure on the affected limb to reduce the chance of pulmonary artery embolism. Conservative treatment: including anticoagulation and thrombolytic therapy. Anticoagulation should be given immediately after the diagnosis is clear to prevent the spread of thrombosis and reduce the recurrence of thrombosis in the future; the drugs include common heparin, low molecular heparin and warfarin. It should be noted that warfarin has not only no anticoagulant effect but also procoagulant effect in the first 3-5 days, so it should be used in combination with low-molecular heparin for 3-5 days when starting warfarin; then stop using heparin and continue to take warfarin orally for 3-6 months, during the process of using warfarin, attention should be paid to monitor the INR (International Normalized Ratio) to maintain between 2 and 3 (some people in China think that it should be maintained between 1.8 to 2.5), within which the side effects of bleeding are less and the therapeutic effect is better. Thrombolytic therapy includes systemic medication or local placement of thrombolytic therapy, commonly used drugs such as urokinase, recombinant tissue-type fibrinogen activator and hemolytic toxins extracted from snake venom; the goal of thrombolytic therapy is to restore venous patency, reduce limb pain and edema, protect valve function and reduce the incidence of post-deep vein thrombosis syndrome. Thrombolysis with systemic drugs has low efficiency, poor effect and large side effect of bleeding; local placement of thrombolysis has high efficiency, good effect and small systemic side effect. Third, surgical thrombus retrieval: including incisional thrombus retrieval and the use of intravascular mechanical thrombus removal, etc. The recent effect can quickly restore the patency of veins, eliminate edema and reduce pain, and the long-term effect includes maintaining the patency of proximal veins and protecting the function of distal venous valves. It should be noted that inferior vena cava filter can intercept thrombus larger than 0.3 cm and reduce the risk of fatal pulmonary artery embolism, but there are many other risks, so it should be used with caution before use, but the filter should be placed to prevent pulmonary artery embolism before intubation thrombolysis and surgical removal of embolus. Compression therapy in chronic period: Wearing elastic stockings when getting out of bed after acute period is the main measure to control swelling, suffocation, pain, weakness and heaviness of lower limbs, and it can also reduce the incidence of syndrome after deep vein thrombosis.