Abstract:In this study，Staphylococcus aureus，Escherichia coli O157，Bacillus cereus，Salmonella，Listeria monocytogenes，Saccharomyces cerevisiae Hansen，Aspergillus niger，Penicillium and Aspergilus flaus were chosen as the tested strains to analyze the antibacterial activity of the peony extract，explore the relationship between pH and bacteriostatic effect of peony extract，finally study the thermal stability of the peony extract.The results showed that the peony extract had obvious inhibitory effect to the bacteria，yeast and mold，and the ability against bacteria（MIC=0.2-0.3）was better than that against yeast（MIC=0.4）and mold（MIC=0.4）.The HCl with the same pH had certain bacteriostasis to tested bacteria，but the effect was significantly lower than the peony extract.In addition，the peony extract had certain thermal stability，bacteriostatic activity of which was not affected under 55℃，and was reduced with the increase of temperature and treatment time，under the condition of 90℃for 20 min，the antibacterial activity of peony extract was lost.