The experimental group use the method of laparoscopic-assisted percutaneous catheter-directed drainage of SAP.According to different causes,.For patients with simple gallbladder stones,it is going to carry out by laparoscopic cholecystectomy or cholecystotomy.For patients with both gallbladder and common bile duct stones,common bile duct exploration is performed.Removing necrotic pancreatic organizations and putting the catheter around the region of pancreas.After the surgery,patient's cavity are continuously douched by catheter using 0.5% 5-fluorouracil normal saline.The postoperation therapeutic program is same as the control group.