Objective To study the effect on expression of high mobility group box-1 （HMGB1） mRNA for the expression of zonula occludens-1 （ZO-1） in ileum tissues， and to explore the possible mechanism of intestinal mucosal barrier injury in rats with acute necrotizing pancreatitis （ANP）. Methods Ninety-six male Wistar rats were divided randomly （random number method） into ANP group， ethyl pyruvate （EP）group， and sham operation group. Eight rats of 3 groups were killed to get abdominal aortic blood and ileal tissues at 6， 12， 24， and 48h after operation， respectively.The levels of plasma amylase （AMY） ， D-lactate acid， and the activity of malonyl dialdehyde （MDA） in the ileum tissues were determined by using automatic biochemical analyzer， improved enzymatic spectrophotometry， and thiobarbituric acid （TAB） colorimetry respectively. The pathological changes of ileum tissues were observed under microscopy by HE staining， the expression of ZO-1 protein in ileum tissues was observed by immunohistochemistry （SP method）， and the expressions of HMGB1 mRNA and ZO-1 mRNA in ileum tissues were detected by reverse transcription-polymerase chain reaction （RT-PCR）. Results Compared with ANP group at the same time， levels of AMY， D-lactate acid， and MDA in ileum tissues of EP group were all significantly lower （P＜0.05）. The expression level of HMGB1 mRNA increased at 6 h while ZO-1 mRNA decreased in ANP group. Compared with ANP group at the same time， the expression level of HMGB1 mRNA of EP group was significantly lower while ZO-1 mRNA was higher （P＜0.05）， and the pathological damage in ileum tissues was lighter. Conclusions The decreased expression of ZO-1 in ileum tissues is one of the vitalcauses for intestinal mucosal barrier injury in ANP， and it probably occurs in case of the excessive expression of HMGB1.