Abstract: Five pairs of primers were designed based on Listeria monocytogenes virulence genes inl B and a pair of well specific primers were selected for this study. The Listeria monocytogenes virulence factor expression was studied by real-time reverse transcriptase PCR. RNAs were extracted from Listeria monocytogenes culture solution under the different environmental factors conditions,and then c DNAs were synthesized respectively.The housekeeping gene 16 S r RNA was used as an internal standard. The changes of the Ct value could mirror the relative expression levels of inl B gene. Our data suggested that inl B gene expression was efficient when the temperature was 15 ℃,p H was 6,the Na Cl concentration was 1.5% to 2%,and the concentration of sucrose was 0.75% to 1.25%. When the temperature was 0 ℃ or 45 ℃,p H was 4 or 9,the Na Cl concentration was more than 3.5%,and the concentration of sucrose was 0% to 0.25%,or more than 2.25%,inl B gene expression was suppressed. What's more,the kinds of acid had little effect on the inl B gene when the p H was 6.