Abstract: Objective To explore the influence of peritoneal lavage therapy at different time on efficacy of severe acute pancreatitis (SAP)patients with intra-abdominal hypertension (IAH). Methods 68 SAP patients with IAH were divided into 3 groups according to time of peritoneal lavage therapy,including group A (n =20,≤24 hours),group B (n =26,>24 hours~≤ 48 hours)and group C (n =22,>48 hours~≤72 hours).APACHE-Ⅱscore was calculated and in-tra abdominal pressure (IAP)was measured before treatment and 7 days after peritoneal lavage therapy.Results APACHE-Ⅱscore and IAP 7 days after peritoneal lavage therapy in all groups decreased significantly (P <0.01).Along with the time delay of peritoneal lavage,the decline of APACHEII score and IAP 7 days after peritoneal lavage decreased gradually (P <0.05).7 days af-ter peritoneal lavage treatment,the degree of decline of IAP in group A was significantly greater than group B (P <0.05).Conclusion Application of peritoneal lavage therapy within 24 hours is the best time for treatment of SAP patients with IAH.