In this study， two strains of Lactobacillus fermentum with high signaling molecule AI-2 were selected as the research objects. D-Galactose， D-ribose and furanone were selected as quorum sensing inhibitors. The AI-2 activity and biofilm formation of the two strains were determined by chemiluminescence method and crystal violet staining method. The results showed that the three inhibitors could inhibit the activity of the signal molecule AI-2 of the two strains of Lactobacillus fermentum. The 200 μmol/L D-ribose had the best inhibitory effect on the activity of AI-2 of strain 2-1， with the inhibitory rate of 19.65%， and 50 μmol/L D-ribose had the best inhibitory effect on the activity of AI-2 of strain 211， the inhibition rate was 28.57%. At the same time， different concentrations of inhibitors had certain inhibitory effect on the biofilm formation of the two strains of Lactobacillus fermentum， but had no significant effect on their growth. The results of scanning electron microscopy showed that the addition of D-ribose had no significant effect on the morphology of the two strains of Lactobacillus fermentum under the biofilm condition， but it could reduce the adhesion of the bacteria.