Indications】 1.Deep vein thrombosis of the lower limbs complicated by pulmonary embolism, and allergic to anticoagulants or have contraindications. 2.Pulmonary artery embolism is still recurrent or aggravated during anticoagulation therapy. 3.During anticoagulation therapy, serious complications (such as intracranial hemorrhage, etc.) occur and force the interruption of anticoagulation therapy. 4.After the pulmonary artery embolism is removed by surgery or intervention, the thrombus still remains in the deep veins of the lower limbs. 5.Patients with large amount of thrombus in the iliofemoral vein or inferior vena cava. 6.Patients who have poor cardiopulmonary function in the past and have lower limb deep vein thrombosis. 7.High-risk group of lower limb deep vein thrombosis or pulmonary artery embolism. Contraindications】 1.Children who have not yet developed. 2.The diameter of the inferior vena cava exceeds 35mm. 3.No inferior vena cava filter placement route (filter delivery may lead to thrombus dislodgement). 4.Proximal occlusion of the inferior vena cava (such as Budd-Chiari syndrome). Procedure】 1.Puncture the femoral vein or jugular vein and place the vascular sheath. 2.Perform inferior vena cava angiography to determine the diameter of inferior vena cava and the presence of inferior vena cava thrombosis, and locate the level of renal vein. The guiding device with filter should be sent into the inferior vena cava at a suitable position, and the head end of the sheath should be 1 cm below the renal vein for the femoral route and 6 cm below the renal vein for the jugular route to avoid the filter affecting the renal vein. If there is thrombus in the inferior vena cava below the opening of the renal vein, the filter can be placed above the opening of the renal vein if necessary. 3.Posterior withdrawal of the outer sheath to place the filter. Inferior vena cava angiography is performed again to clarify the position of the filter and the inferior vena cava blood flow. 4.Remove the filter guide sheath, remove the vascular sheath, compress the puncture site to stop bleeding, and apply pressure to dress the puncture site. Precautions】 1.Usually perform inferior vena cava angiography to determine the diameter of inferior vena cava and accurately locate the location of renal vein before filter placement. 2.Place the inferior vena cava filter under the renal vein as much as possible. 3.Anticoagulation therapy should be performed after the operation.