Deep vein thrombosis (DVT) is a common vascular surgery disease in clinical practice. In the acute stage of the disease, swelling, pain and thrombus dislodgement of the affected limb can lead to pulmonary embolism, which is life-threatening; in the chronic stage, there are limb swelling, superficial varicose veins, eczema and chronic skin ulcers, which lead to limb disability and seriously affect the quality of life. Venous injury, slow blood flow and venous injury are the three main causes of this disease. So what are the specific risk factors? 1.Surgery, trauma Orthopedic (especially spine, lower limb) surgery and pelvic surgery can greatly increase the risk of DVT, and the prolonged anesthesia increases this risk. 2.Medical diseases Nephrotic syndrome, tumor, acute myocardial infarction, congestive heart failure, acute respiratory distress syndrome, systemic lupus erythematosus, diabetes mellitus, etc. 3, pregnancy and contraceptives 4, age and lifestyle Age ≥ 40 years DVT incidence increased significantly, prolonged fixed position (prolonged squatting, sedentary), reduced water consumption, gender, race, obesity, dietary habits, smoking, seasonal changes, etc.