Lower extremity deep vein thrombosis is one of the most common clinical diseases, which refers to the formation of blood clots in the veins of lower extremities, resulting in pain, swelling and skin bruising in the early stage of the affected extremity; in the acute stage, pulmonary embolism may occur at any time due to the dislodgement of the thrombus and the formation of emboli, leading to sudden death in severe cases. In developing countries, there are about 30-60 million people suffering from the disease every year, and in the United States, there are 600,000 people suffering from venous thromboembolic disease every year. Despite anticoagulation and thrombolytic treatment by drugs, 7% of thrombosis recur within six months after the first attack; about 20-50% of DVT occur in 1-2 years with post-thrombotic syndrome; the incidence of PTS will reach 50%-82% in 5 years; 5-10% of patients have serious symptoms such as pain and swelling of the affected limb, calf ulcer, difficulty in walking, etc., which often consume a lot of medical resources and impose a heavy burden on families and society. It often consumes a lot of medical resources and causes a heavy burden to families and society. Deep vein thrombosis in the lower extremities leads to significant coarsening of the affected limbs, and post-deep vein thrombosis syndrome, blood flow stagnation, blood hypercoagulation and vascular wall damage are the three main factors causing venous thrombosis. One of these factors may play a dominant role, and the other factors complement each other to form the thrombus. Any situation involving the above factors such as trauma, tumor, surgery, long-term bed rest, pregnancy, etc. can trigger the formation of venous thrombosis. DVT can occur in any part of the veins of the lower extremities, and the symptoms can be mild or severe depending on the location of the thrombosis. About 2/3 of DVT is asymptomatic, but if the venous thrombus is dislodged, it can cause a pulmonary embolism with more serious consequences. When pulmonary embolism occurs, cough, chest pain, dyspnea, and even cyanosis, shock, and sudden death can occur. In order to further determine the site, degree and scope of lesion, ultrasonic examination can be taken. This method is the more commonly used examination method. The ultrasound can directly observe the diameter of the vein and the lumen, and can understand the extent of the venous thrombosis and its location. Real-time color flow Doppler imaging has good specificity and sensitivity (up to 95%) for above-knee deep vein thrombosis, and a few patients require venography. The traditional treatment methods for DVT are mainly anticoagulation, thrombolysis and tethering. The greatest risk of lower extremity venous thrombosis is thrombus dislodgement leading to pulmonary embolism, which can lead to death in some patients. The main methods to prevent pulmonary embolism in the acute phase of thrombosis are inferior vena cava filter implantation and lower extremity braking. Inferior vena cava filter implantation is required to reduce the chance of fatal pulmonary embolism in patients with recurrent pulmonary embolic events, floating thrombi in the veins, or when deep vein retrieval or thrombolytic therapy is required. Inferior vena cava filter implantation Anticoagulation therapy has the ability to prolong clotting time and prevent thrombus growth, propagation, and recurrence, but it does not dissolve formed thrombi. Venous tethering is more controversial. Venous tethering improves venous patency and has good immediate efficacy, but surgical treatment has a high thrombus recurrence rate and the time window for surgery should be within 48-72 hours of onset. Removed venous thrombus Therefore, the more consistently agreed indications for surgery are patients with severe symptoms of iliofemoral vein thrombosis, such as femoral cyanosis, who are at risk of limb necrosis. Currently, thrombolytic therapy based on anticoagulation is being widely used. Direct thrombolytic therapy via catheter is superior to systemic medication and has a higher thrombolytic efficiency. Thrombolytic catheters can be placed through the healthy femoral vein, internal jugular vein, or foot vein, but the N vein placement route is more commonly used. Thrombolysis of the N vein is a new way of treating deep vein thrombosis in the lower extremities by using endovenous techniques such as thrombolysis of the N vein, balloon dilation and shaping, and iliac vein stent implantation, which can significantly improve the rate of thrombosis and reduce the incidence of post-thrombotic syndrome in the near and medium term. The specific treatment is bed rest with elevation of the affected limb for 15-30º daily subcutaneous injection of low molecular heparin, pumping of urokinase via intravenous cannula, and adjustment of urokinase dosage according to the coagulation series index. A venogram is performed via N vein placement, and depending on the findings and the patient’s actual condition, termination of intravenous luminal therapy or further intravenous luminal therapy, such as intravenous balloon dilation or iliac vein stenting, is chosen. Prior to discharge, oral warfarin was started and the PT-INR was adjusted to about 2.0. After discharge, patients are required to be anticoagulated and wear medical compression stockings for a long time. Lower limb venous thrombosis has such a great threat to patients, leading to pain and swelling of the affected limbs, calf ulcers and other serious symptoms, which seriously affects the quality of life of patients and causes heavy burden to families and society. So, how can we prevent the occurrence of deep vein thrombosis in general? Pay attention to the following points can reduce the risk of venous thrombosis: 1, avoid prolonged immobility, you should get up every certain time to walk around, move the lower limbs, drink an appropriate amount of water to avoid blood thickening and promote venous blood return; 2, for postoperative, postpartum and other long-term bedridden patients, patients should be encouraged to carry out active activities of the lower limbs in bed, and make deep breathing and coughing movements; those who can get up should get out of bed as early as possible to promote calf muscle activity and increase the risk of venous thrombosis. For those who can get up, they should get out of bed as early as possible to promote the movement of calf muscles and increase the venous return of lower limbs; 3. 6.Patients with high risk of thrombosis should wear antithrombotic stockings to reduce the incidence of thrombosis, and patients should wear medical elastic stockings for a long time after treatment of deep vein thrombosis to prevent the sequelae of deep vein thrombosis.