The infected pancreatic necrosis (IPN) should be treated by debridement and drainage. In recent years, the results of clinical research show that minimally invasive debridement such as video-assisted (laparoscope, nephroscope, endoscopy, etc.) and total laparoscopic debridement can significantly improve the prognosis of IPN patients. After a long period of clinical practice, laparoscope-assisted debridement was selected as the main surgical method in our center. In many large-scale clinical studies, patients after surgery underwent necrotic cavity lavage (such as small omental sac lavage, retroperitoneal space lavage, peripancreatic lavage, etc.), but its necessity and clinical significance were not clearly stated in the guidelines. At present, the clinical research mainly focuses on the improvement of minimally invasive debridement, and less on the necessity of lavage. In the past, necrotic cavity lavage was performed in IPN patients, but long-term clinical observation showed that lavage may lead to spread of infection and increase the incidence of lower extremity venous thrombosis which is not accorded with ERAS(Enhanced Recovery After Surgery). Therefore, since 2012, our center has stopped necrotic cavity lavage for IPN patients after debridement. We retrospectively analyzed the therapeutic effect from February 2014 to August 2017 and found that even without necrotic cavity lavage, better therapeutic effect could be achieved. Meanwhile it can simplify the operation process and avoid infection spread. This treatment method provides a new idea. However, it is a retrospective study not a randomized controlled trials(RCT) which is low effectiveness of proof. Therefore, we design this RCT to verify the necessity of necrotic cavity lavage after laparoscope-assisted debridement for patients with infected pancreatic necrosis.