The incidence of severe acute pancreatitis (SAP) is increasing year by year,and the mortality is high,which poses a great threat to the life of patients.In recent years,the immune nutrition therapy has become the focus in the treatment of SAP,among which,fish oil lipid emulsion as a novel type of fat emulsion,has the multi-effects of anti-inflammatory,anti-oxidative,immunomodulatory,promoting signal transduction and protecting organ function apart from providing nutrition and regulating metabolism.It can prevent the deterioration of the whole body from systemic inflammatory response syndrome (SIRS) to multiple organ dysfunction syndrome (MODS and ultimately improve the prognosis of patients.