Already in 1865 Trousseau noted that patients with gastric cancer were prone to deep vein thrombosis of the extremities, and now thromboembolism (VET) is considered an important cause of death in patients with malignancy. Deep vein thrombosis (DVT) is the most common thromboembolic disease in oncology patients. Once DVT is formed, basic and specialized nursing care should be strengthened and closely monitored to control the development of disease and complications as much as possible. 1.General care: (1) In the early stage of deep vein thrombosis, patients should rest in bed to reduce the chance of pulmonary embolism due to the dislodgement of thrombus by walking, and avoid massaging and squeezing the swollen limbs; (2) The bed rest time is usually about 2 weeks, and after 2 weeks, you can wear elastic stockings or wrap the affected limbs with elastic bandages to speed up the tissue swelling and reduce the symptoms; (3) After 2 weeks, daily moderate exercise, in principle, at least (3) After 2 weeks, exercise moderately every day, in principle, at least 10 minutes of continuous exercise every day. (4) Take the medication as prescribed by the doctor, monitor the prothrombin time regularly during the application of anticoagulants, and observe whether there is abnormal bleeding at the puncture site, nose and gingival area, and whether there is hematuria and black stool; (5) When using anticoagulant, dissipative or thrombolytic drugs through the vein, it is better to choose the vein distal to the affected limb; (6) If the patient suddenly develops symptoms such as chest pain, shortness of breath, cough and hemoptysis, he should be alert to the occurrence of pulmonary embolism and report to the doctor for early diagnosis and treatment. (2) Observe the degree of swelling and changes in skin temperature of the affected limb, measure and record the circumference of the affected limb in different planes daily, and observe the changes to assist the doctor in judging the efficacy of the treatment; (3) Prevent and eliminate the causes of ulcers, wash the foot daily, and once there is an ulcer (4) For patients with deep vein thrombosis in the lower limbs, the affected limbs should be elevated above the heart level to facilitate blood return and promote the swelling to subside; give therapeutic positions, specifically: lower limbs elevated 25 degrees, knee flexion 15 degrees, this position can make the iliofemoral vein into a relaxed and non-compressed state. It can also relieve the strain of N vein. 3, life care: (1) the diet should be light, give low-fat diet, reduce salt intake, eat more fiber, fresh vegetables and fruits and black fungus and other foods that reduce blood viscosity; (2) should strictly abstain from smoking, nicotine in the cigarette can cause peripheral vasoconstriction blood flow is reduced, the intima changes cause cholesterol deposition. (3) Keep the bowels open to reduce the impact of lower limb venous reflux due to forceful defecation and increased abdominal pressure. The classical Virchow theory suggests that vascular wall damage, blood flow abnormalities and blood composition changes are the three main factors causing venous thrombosis. (1) Tumor cells can activate the coagulation and fibrinolytic system by releasing their own procoagulant factors or stimulating the procoagulant activity of other cells (endothelial cells, monocytes-macrophages, platelets, etc.); (2) Antitumor therapy (drugs, radiotherapy, surgery, etc.) often leads to vascular wall damage and activates the coagulation mechanism; (3) Prolonged bed rest, tumor compression, etc. lead to blood flow problems in the patient. (4) Nutritional disorders, hypoxia, increased plasma globulin, increased plasma fibrinogen and other factors lead to increased blood viscosity; (5) Due to the need for long-term intravenous medication, central venous cannulae are increasingly used in oncology departments, which not only damage the venous wall, but also easily form thrombus on the surface of the cannulae. On the contrary, the hypercoagulable state has promoted the growth of tumor cells, metastasis and tumor blood vessel formation, which accelerates the deterioration of tumor. With the increase of clinical attention and the prolongation of survival of tumor patients, the incidence of combined DVT in malignant tumors is gradually increasing, which has been statistically shown to be the 2nd most common complication of tumors, mostly suggesting late stage of disease and high tumor load in patients. Since the occurrence of thromboembolic events in oncology patients cannot be predicted yet, routine preventive strategies are particularly important. For patients undergoing surgery and chemotherapy, especially those with hypercoagulable states, some scholars advocate the administration of low-dose plain heparin or low-molecular heparin prophylaxis, the safety and efficacy of which need to be further confirmed.