Objective To explore the effect of neostigmine in treatment of severe acute pancreatitis (SAP) combined with intra-abdominal hypertension (IAH).Methods 42 patients diagnosed as SAP combined with IAH and meeting standard were collected from Aug.2012 to Jul.2016 in our hospital.They were randomly divided into two groups:observation group and the control group.General information of the two groups was comparable.Patients of the control group received conventional treatment methods such as fasting,gastrointestinal decompression,nutritional support,antispasmodic,analgesia,intravenous infusion of omeprazole and octreotide.Patients of the observation group received intramuscular injection of neostigmine methylsulfate on the basis of the control group for seven days.The intra-abdominal pressure,recovery time of bowel sounds,the first exhaust and defecation time,remission time of abdominal distention,modified Marshall score,APACHE-Ⅱ score,SIRS score,total hospitalization time and total hospitalization expenses,MODS rate,operation rate and mortality of the two groups were recorded during the treatment.Results The intra-abdominal pressure of the observation group was (14.25±1.03) mmHg,(13.52 ±1.23) mmHg,(12.73±1.14)mmHg respectively,lower than that of the control group (15.14± 1.12) mmHg,(14.60± 1.11) mmHg,(13.84±1.08) mmHg at the 3rd,4th,and 5th day after treat ment (P＜0.05).For the observation group,the recovery time of bowel sounds was (7.24±1.35) d,the first exhaust and defecation time was (11.33±1.51) d,(8.36±1.63) d,remission time of abdominal distention was (13.62±2.26) d,lower than those of the control group ((9.56±1.17)d,(13.42±1.26)d,(10.45±1.54)d,(16.75±3.05)d) (P＜0.05).The recovery time of bowel sounds,the first exhaust and defecation time,remission time of abdominal distention of the observation group were lower than those of the control group (P＜0.05).The modified Marshall score,APACHE-]Ⅱ score,SIRS score of the two groups had no significant difference (P＞0.05).The total hospitalizationtime and total hospitalization expenses of the two groups had no significant difference (P＞0.05).MODS rate,operation rate and mortality of the two groups had no significant difference (P＞0.05).Conclusions Neostigmine can significantly reduce intra-abdominal pressure of patients suffering from SAP combined with IAH,improve the symptoms of paralytic ileus,promoting exhaust and defecation.However,it has limited effects on prognosis of patients suffering from SAP combined with IAH.