Abstract: Objective To evaluate the effect of sustained low-efficiency diafiltration(SLEDF) on intestinal mucosal barrier dysfunction and immune dysfunction in patients with severe acute pancreatitis（SAP）.Methods Fifty-one patients with SAP were randomly divided into continuous veno-venous hemofiltration(CVVH) group with 25 patients and SLEDF group with 26 patients,CVVH and SLEDF were treated separately on the basis of routine treatment.Prognosis,recovery time for blood and urine amylase,blood D-lactic acid,endotoxin(ET),diamine oxidase(DAO),CD3⁺,CD4⁺,CD8⁺ T lymphocyte levels,CD4⁺/CD8⁺ T lymphocyte ratio before and on the 2nd,4th,8th,14th day after treatment,complications related to blood purification were collected and compared in the two groups.Results There were no significant differences between the two groups in the mortality rate and the recovery time of blood and urine amylase,there were no significant differences in blood D-lactic acid,ET,DAO,CD3⁺,CD4⁺,CD8⁺ T lymphocyte levels,CD4⁺/CD8⁺T lymphocyte ratio between the two groups before and on the 2nd,4th,8th,14th day after treatment（P>0.05）.The levels of D-lactic acid,ET and DAO in both groups were lower on the 2nd,4th,8th,14th day after treatment,the levels on the 8th and 14th day were lower than those on the 4th day（P＜0.05）.CD3⁺,CD4⁺ T lymphocyte levels,CD4⁺/CD8⁺ T lymphocyte ratio in the two groups on the 4th,8th,14th day were higher than those in the same group before treatment,the levels on the 8th and 14th day were higher than those on the 4th day（P＜0.05）.CD8⁺ T lymphocyte level in the two groups on the 4th,8th day were lower than those in the same group before treatment,the levels on  the 8th and 14th day were lower than those on the 4th day（P＜0.05）.Conclusion SLEDF and CVVH could improve intestinal mucosal barrier dysfunction and immune dysfunction in SAP patients.SLEDF is worth popularizing in clinic because of convenient operation and low medical cost.

Key words: Severe acute pancreatitis, Sustained low-efficiency diafiltration, Intestinal mucosal barrier dysfunction, Immune dysfunction