Abstract： Objective： To discuss the effect of calycosin on acinar cell injury in severe acute pancreatitis(SAP) and its molecular mechanism. Methods：Pancreatic acinar AR42J cells of rats were divided into the Con group(AR42J cells)，the SAP group(AR42J cells+10 nmol/L caerulein +10 mg/L lipopolysaccharide)，the SAP+Calycosin-L group(AR42J cells+10 nmol/L caerulein+10 mg/L lipopolysaccharide+10 μmol/L calycosin)，the SAP+Calycosin-M group(AR42J cells+10 nmol/L caerulein+ 10 mg/L lipopolysaccharide+50 μmol/L calycosin)，the SAP+Calycosin-H group(AR42J cells+10 nmol/L caerulein+10 mg/L lipopolysaccharide + 100 μmol/L calycosin)， the SAP + si- NC group(AR42J cells + 10 nmol/L caerulein + 10 mg/L lipopolysaccharide + transfected si- NC)， the SAP + si- TREM- 1 group(AR42J cells + 10 nmol/L caerulein + 10 mg/L lipopolysaccharide+transfected si-TREM-1)，the SAP+Calycosin+pcDNA group(AR42J cells+10 nmol/L caerulein+10 mg/L lipopolysaccharide+100 μmol/L calycosin+transfected pcDNA)，the SAP+Calycosin+pcDNA-TREM-1 group(AR42J cells+ 10 nmol/L caerulein+10 mg/L lipopolysaccharide+100 μmol/L calycosin+ transfected pcDNA-TREM-1). The levels of tumor necrosis factor-α(TNF-α) and interleukin-6(IL-6) were measured by enzyme-linked immunosorbnent assay. Cell apoptosis was detected by flow cytometry. Western blot method was used to detect the protein expression of B-cell lymphoma-2 gene (Bcl- 2)， Bcl- 2- associated X protein(Bax)， cleaved cysteinyl aspartate specific proteinase3(cleaved- caspase3)， and triggering receptor expressed on myeloidcells-1 protein(TREM-1). The expression of mRNA of TREM-1 was detected by real time fluorescence quantitative PCR(RT-qPCR). Results：Compared with those in the Con group，in the SAP group，the cell apoptosis rate，and the levels of IL-6 and TNF-α，the protein expression of Bax，and cleaved-caspase3，as well as the expression of mRNA and protein of TREM-1 were increased(P＜0.05)；the protein expression of Bcl-2 was decreased(P＜ 0.05). Compared with those in the SAP group，in the SAP+Calycosin-L group，the SAP+Calycosin-M group，and the SAP+ Calycosin-H group，the levels of IL-6，TNF-α，the protein expression of Bcl-2，and the expression of mRNA and protein of TREM-1 were decreased in SAP acinar cells(P＜0.05)；the apoptosis rate，and the protein expression of Bax and cleaved caspase3 were increased in a concentration-dependent manner(P＜0.05). Compared with those in the SAP+si-NC group，in the SAP+si-TREM-1 group，the protein expression of TREM-1 and Bcl-2，and levels of IL-6 and TNF-α were decreased in SAP acinar cells(P＜0.05)；the apoptosis rate，and the protein expression of Bax and cleaved-caspase3 were increased(P＜ 0.05). Compared with those in the SAP+Calycosin+pcDNA group，in the SAP+Calycosin+pcDNA-TREM-1 group，the levels of IL-6 and TNF-α，and the protein expression of TREM- 1 and Bcl-2 were increased in acinar cells(P＜0.05)；the cell apoptosis rate，and the protein expression of Bax and cleaved- caspase3 were decreased(P＜0.05). Conclusion：Calycosin can relieve inflammation of SAP acinar cells by regulating the expression of TREM-1，induce cell apoptosis，and protect SAP acinar cells from injury.