The control group use the method of conventional conservative therapy without surgical management,the principles of treatment include:(1)fasting,insert gastric tube,gastrointestinal decompression;(2)complement of blood volume,keeping water ,electrolyte and acid base balance;(3)inhibiting pancreatic enzyme and acid secretion;(4)using broad-spectrum antibiotic at the early phase;(5)improving microcirculation,dextrans and FuFangdanshen by IV;(6)early parenteral nutrition;(7)treatment by chinese herbs;(8)strengthen the function of important organs.