The matters that need to be paid attention to after deep vein cannulation include keeping the cannula fixed, sterilizing the puncture point and the local area, standardizing the care of the cannula, and regularly monitoring the changes of the cannula, etc. Standardized care is needed to avoid infections and so on. 1. Keeping the cannula fixed: it is necessary to keep the deep vein cannula fixed, avoiding pulling and pulling to cause the cannula to fall off, avoiding strenuous activities. 2. Sterilize the puncture point and local wound: it is necessary to change the dressing in time, pay attention to aseptic operation, keep the puncture point clean after tube placement to avoid infection, and change the dressing regularly to keep the local dryness. 3. Standardize the care of tube placement: after giving medicine through the tube, it needs to be flushed with saline to avoid blockage, and standardize the use of heparin cap for anticoagulation. 4. Regularly monitor the changes of tube placement: after tube placement, it is necessary to observe the changes of local conditions, whether the skin is swollen or not. After DVT placement, standardized care should be carried out strictly under the guidance of doctors to avoid infection, detachment and other symptoms, and timely medical treatment is needed to avoid deterioration of the situation.