Deep vein thrombosis (DVT) of the lower extremities is a common clinical disease, the incidence of which is increasing year by year. The main clinical manifestations are swelling, pain, superficial venous dilatation, increased skin temperature and hypothermia in the lower extremities, femoral bruising in severe cases, and thrombus dislodgement into the lungs can cause complications of pulmonary embolism (PE), which can lead to patient death in severe cases. The pathogenic factors include obesity, history of venous thrombosis, varicose veins, abnormal coagulation mechanism, diabetes, oral contraceptives, trauma, and childbirth. In the early stage of lower extremity deep vein thrombosis, due to the obstruction of veins by thrombus, the venous blood return is impaired, and the limbs become swollen, painful and restricted in activities; in the later stage, the thrombus in the veins is mechanized and recanalized, the diseased veins are narrowed, dilated and tortuous, the venous valves are destroyed, the deep vein blood flows backward to the superficial veins, causing the superficial veins of the lower extremities to stagnate, the venous pressure rises, the tissues are hypoxic, and finally the lower extremity deep vein thrombosis post The main clinical manifestations of PTS are recurrent lower limb swelling, varicose veins, skin pigmentation, eczema-like dermatitis, secondary infection and chronic venous ulcers of lower limbs. It is difficult to treat clinically, and some of the affected limbs are in a long-term wasted state, which seriously affects the quality of life of patients. Therefore, for deep vein thrombosis of lower limbs, early diagnosis and treatment is recommended to dissolve the thrombus as soon as possible and restore blood return, so as to protect the function of venous valves and prevent the occurrence of post-thrombotic syndrome. In our department, we have achieved good results in the treatment of lower limb deep vein thrombosis by thrombolysis via small saphenous vein placement. The interventional minimally invasive technique inserts the thrombolytic catheter through the small saphenous vein into the lesioned vessel in a smooth manner, which increases the contact area between the thrombolytic drug and the thrombus and shortens the time for the thrombolytic drug to reach the thrombus site, thus greatly improving the local concentration of the thrombolytic drug at the lesioned site and achieving the best thrombolytic effect of the highly concentrated thrombolytic drug in the shortest time, and reducing the occurrence of systemic bleeding complications without damaging the venous valves and maximizing the preservation of the deep vein valves. The normal function of deep vein valves is preserved to the maximum extent. To prevent the occurrence of pulmonary embolism due to thrombus dislodgement, an inferior vena cava filter should be routinely placed before catheter thrombolysis. Postoperative treatment is combined with elastic stockings, anticoagulation, and de-agglomeration. The greatest advantage of this method is that it is minimally invasive, does not damage the venous valves in the direction of blood flow, does not require puncture of the contralateral femoral vein, and reduces the risk of contralateral deep vein thrombosis that may result from thrombolysis by cannulation through the contralateral femoral vein.