Inferior vena cava filter (IVCF) is a filtering device designed to prevent pulmonary embolism caused by dislodged thrombus in the deep veins of the lower extremities and iliac veins that travels up the inferior vena cava. Depending on the method of use, IVCFs can be divided into permanent filters, retrievable filters and temporary filters. Permanent filters are left in the body for a long time and theoretically do not need to be removed, but as the time lengthens, the rate of complications associated with the filter increases significantly. The emergence of retrievable filters remedies these deficiencies to a certain extent, as they can be removed by grasping and other methods after a certain period of time in the body, and the time window for removal is determined by the time of endothelialization of the filter in contact with the inferior vena cava, after which they can be retained as permanent filters. Temporary filters have a fixed catheter, which is released and then fixed under the skin of the neck through the right internal jugular vein, and can be removed by cutting the skin of the neck and pulling the catheter. The placement of an inferior vena cava filter is an invasive prophylaxis and carries certain risks, with a high incidence of complications such as bleeding, perforation, and fracture. Inferior vena cava filters prevent only large thrombi and do not prevent small thrombi from entering the pulmonary circulation, so the indications for inferior vena cava filter placement should be strictly controlled. The currently accepted indications for filter placement can be divided into absolute indications and relative indications. (1)Absolute indications 1.Patients with pulmonary embolism or inferior vena cava and iliac, femoral and popliteal vein thrombosis have one of the following conditions: (1)Contraindication to anticoagulation therapy; (2)Complications such as bleeding during anticoagulation therapy; (3)Recurrence of pulmonary embolism even after adequate anticoagulation therapy and various reasons for failure to achieve adequate anticoagulation. 2.Pulmonary embolism with concurrent lower extremity deep vein thrombosis. 3.There is free floating thrombus or large amount of thrombus in the iliac, femoral vein or inferior vena cava. 4.Diagnosed with easy embolism and repeated pulmonary embolism. 5.Acute lower limb deep vein thrombosis, who want to perform transcatheter thrombolysis and incisional thrombectomy. (B) Relative indications Mainly for prophylactic filter placement, which must be selected with caution. 1.Severe trauma with or likely to have lower extremity DVT, including: (1) closed craniocerebral injury; (2) crestal marrow injury; (3) multiple long bone fractures or pelvic fractures of lower extremities, etc. 2, Critical cardiopulmonary reserve with lower extremity deep vein thrombosis. 3, chronic pulmonary hypertension with hypercoagulable state. 4, Patients with high risk factors, such as long-term limb braking, intensive care patients. 5.Old age, long-term bed-ridden with hypercoagulability. Inferior vena cava filter placement is not necessary for most patients with lower extremity DVT. Strict anticoagulation therapy can effectively reduce the incidence of pulmonary embolism. Even if an inferior vena cava filter is placed, formal anticoagulation therapy is still needed to reduce both thrombosis and the chance of DVT dislodgement.