Abstract: To study the relationship between AI- 2 /LuxS quorum sensing and biofilm formation in Lactobacillus plantarum HE-1.To amplify the luxS gene and analyse the homology and phylogenetic level of luxS gene fragments with other Lactobacilli.AI-2 produced by Lactobacillus plantarum HE-1 were verified with the method of molecular biology.Using the method of bioluminescence to detect the fluorescence, Lactobacillus plantarum HE-1 in different culture time AI-2 production were measured.Biofilm formation was measured in different time points by the method of microplate.The luxS gene fragment was amplified by PCR, and the homology and phylogenetic of luxS gene fragments were analysed.Experiment results showed that the amount of biofilm was identical with the production of AI-2 signal molecules.The luxS gene was amplified successfully, the luxS gene homology analysis showed strain HE-1 and other Lactobacillus species luxS gene had close genetic relationship.It could be speculated that biofilm formation was closely related to the AI-2 /LuxS quorum sensing system.The homology analysis of luxS gene further demonstrated that AI-2 was produced by Lactobacillus plantarum HE-1.