In the treatment of abdominal infections and intestinal fistulas, the double trocars are very useful. The physicians from Nanjing General Hospital of Nanjing Military Region (including postgraduate students, advanced studies and postdoctoral work) all refer to this double trocar as “Lai’s double trocar” to show their respect for academician Lai Jieshou. Since the invention of the double trocar by Dr. Lai, the infected material in the abdominal cavity has been adequately drained and a great breakthrough has been achieved in the control of the source of infection. The advent of the double cannula drainage technique, in conjunction with the development of nutritional support techniques at the time, led to a fundamental change in the philosophy of enterocutaneous fistula treatment. The morbidity and mortality rate for enterocutaneous fistulae and abdominal infections has also decreased from 50-60% previously to less than 20% currently, and the rate of re-fistulae after enterocutaneous fistulae has decreased significantly. The double trocar, unlike the abdominal drainage tubes commonly used in surgery today, is a negative pressure drainage device that is continuously flushed and is a form of active drainage, whereas most of the drainage commonly used in surgery today is passive drainage. The double trocar system consists of two parts: negative pressure drainage and flushing. The negative pressure drainage part is subdivided into two parts: the outer tube and the internal suction tube, with a closed blind end at the front of the outer tube. When postoperative abdominal infection and intestinal fistula occur, the control of the source of infection is extremely important. Poor control of the source of infection, i.e. poor abdominal drainage, will produce a series of complications that are difficult to correct, such as hemorrhage, septic shock, severe malnutrition, severe water, electrolyte and acid-base imbalance, and even acute lung injury, acute kidney injury, etc. The timely and effective abdominal drainage can reduce the occurrence of these conditions. In clinical work, we often encounter patients with enterocutaneous fistulas transferred from outside hospitals with thick dressings covering the fistula, which is locally red, swollen, and ulcerated. The first step in our treatment is often to remove all dressings, remove the original latex abdominal drainage tube and replace it with a double cannula, and the symptoms of the local skin and trauma of the patient’s intestinal fistula quickly improve significantly. We also often encounter patients with enterocutaneous fistulas accompanied by abdominal bleeding, and after replacing them with double cannulae, the bleeding symptoms improve due to adequate drainage of the abdominal infection. In many patients with tubular fistulae, the fistula can even be closed after adequate drainage with a double trocar, eliminating the need for reoperation. However, there are two sides to everything. The double cannula also has this problem and should always be used by an experienced specialist. During the application of the double cannula it is important to keep the drainage open, to keep the drainage flow not less than the flushing volume, to observe the color of the drainage fluid frequently, and to treat it promptly in case of bleeding. When replacing external drains with double cannulae, it is best to first perform an imaging examination via the original drainage tube to understand the direction, length and sinus tract of the original drainage tube, so as to have a good idea. At the same time, the type of double trocar should be selected according to the thickness of the external drainage tube (medium-sized tube, standard tube and miniature double trocar). In conclusion, double trocars are an important part of the treatment process of abdominal infection and intestinal fistula. Many lives of patients with severe abdominal infections and complicated intestinal fistulas have been saved due to the application of double trocars. The use of double trocars is safe and effective. We hope that more patients with abdominal infections and enterocutaneous fistulas will benefit from them.