Abstract: In order to research the inhibiting effect of 3, 4-dibromo-2 ( 5 H) -furanone ( DF) on biofilm formation of Pseudomonas Fluourcens.The effect of DF on minimum inhibitory concentration ( MIC) , minimum bacterial concentration ( MBC) values and growth curve of Pseudomonas fluorescens according the biofilm model of 24 orifice plate and silicon rubber were calculated by CFU counting method.The biofilmand the cluster movement ability of bacteria was studied at MIC and 5 MIC of DF, and the inhibiting rate of formation the contents of total protein synthesis and polysaccharide were examined.The results showed that the MIC and MBC values of DF on Pseudomonas fluorescens were 12.5 μg/m L and 800 μg/m L, respectively. The inhibitting rates of biofilm formation of Pseudomonas fluorescens were 20.59% ± 2.91% and 99.54% ± 1.83% on 24 h at the concentration of 1 MIC and 5 MIC of DF.DF could inhibite the cluster movement and disturb the quorum sensing, there by had an effect on the total protein and extracellular polysaccharides content of Pseudomonas fluorescens.The inhibitting rates of total protein and extracellular polysaccharides content of Pseudomonas fluorescens were 8.04% ± 0.37% and 51.08% ± 2.71% on24 h at the concentration of 5 MIC of DF.In this paper, the reason of DF's effect on the formation of Pseudomonas fluorescens biofilm was studied.The inhibition of DF on Pseudomonas aeruginosa biofilm formation and its interference with QS pathway have good theoretical and practical reference.