Objective To investigate the significance of applying a homemade closed negative pressure suction device to treat severe infected wounds of the lower extremities. Methods Thirty-five patients with severe infected lower limbs with soft tissue defects were treated with a homemade simple negative pressure suction device and debridement was performed at each change of the negative pressure device. After 10-63 days of treatment, with an average of 18 days, a second-stage free skin graft or flap transfer repair was performed on the trauma surface. After treatment, 35 patients had clean wounds with smaller areas and fresh granulation growth, and the free implant or flap transfer repair wounds were successfully repaired in one visit. Conclusion Homemade simple negative pressure suction combined with intermittent debridement can effectively control wound infection, promote necrotic material detachment, accelerate healing, and create conditions for wound repair. The skin and soft tissues of human lower extremities are under high tension, and the treatment of lower extremity trauma usually requires skin grafting or flap transfer to repair, but if the trauma has a lot of necrotic material and infection seriously restricts the repair and reconstruction surgery, the condition will be prolonged or even worsened. From 2005 to 2009, 35 patients with severe infected wounds of the lower extremities were treated with closed continuous negative pressure suction and intermittent thorough debridement with satisfactory results, which created good local conditions for the second stage of surgical repair and effectively shortened the preoperative preparation time. 1. Severe infected trauma of the lower extremity is a broad definition, mostly secondary to trauma, lower extremity ischemia, diabetes, etc. In addition, the blood flow of human lower extremity is weaker than other parts of the body, and the skin tension is high, the tissue looseness is poor, and the local mobilizable tissue is limited, thus making the trauma repair more difficult. For the treatment of infected wounds or chronic wounds of the lower extremity, we usually use skin grafting or flap transfer surgery, which have strict indications and require fresh wounds and rich blood supply. The exposed bone, tendon, or blood vessels force us to use more complex flap transfer repair procedures. In terms of wound repair alone, we have a variety of treatment modalities, but the principle of treatment for such patients should be the simplest and most effective method to repair the wound in the shortest possible time, thus creating an irreconcilable contradiction between treatment principles and feasible options. Negative pressure closure trauma therapy (VAC) is a new trauma treatment method that has emerged in the last decade, which is achieved by special equipment and has a significant effect on the treatment of trauma. According to our experience, after a certain period of VAC treatment, the timing of surgery gradually emerged in some cases that were originally inoperable, cases that could only undergo complex flap transfer repair could be converted to relatively simple skin graft repair, and cases that originally required skin grafting could even heal on their own, bringing a surprise to the repair treatment of such wounds. Therefore, in the early stage of treatment, we should focus on how to create surgical indications in the surgical exclusion zone, so as to transform the inoperable trauma into an operable one, thus realizing our treatment principle of “minimizing the big things and minimizing the small ones”. 2, the lower extremity trauma individual differences, even though the trauma area is the same, but because of the location, the causes, the patient’s own conditions and many other factors largely affect the healing process, according to our experience, the nutritional status of patients, not accompanied by systemic diseases of the lower extremity trauma caused by trauma or infection, their own healing ability, VAC treatment effect is particularly obvious, can significantly Therefore, for patients with vascular lesions or diabetes, local treatment of lower extremity trauma requires active treatment of the primary disease in order to obtain satisfactory results. VAC drains a large amount of exudate from the trauma and reduces the local edema, and because there is a lot of infected necrotic material and bacteria in the exudate, it can effectively reduce the number of local bacteria and promote local blood circulation. This improves the condition of the wound surface. The physical effect of mechanical pulling through the negative pressure replaces the normal extracellular matrix stimulating cell proliferation, and the local cellular value added marks the restart of the wound healing process. The presence of a large number of proteolytic enzymes, especially metalloproteins and cytokines, in the exudate of the wound surface weakens the role of the extracellular matrix for wound healing, and VAC is able to remove such toxic substances in time to provide conditions for wound healing. 4. Advantages in clinical work: reduce the frequency of drug change and wound cleaning, a successful negative pressure closure can remain effective for 3-5 days, reducing the pain of patients when changing drugs while reducing the labor intensity of medical personnel, transparent film is convenient to observe the local tissue healing or exudation at any time.