Abstract: The inhibition effect of anthocyanin extracts from Rhodomyrtus tomentosa(Ait.)Hassk on the biofilm of Pseudomonas lundensis and Pseudomonas fluorescens were researched in this study. The minimum inhibitory concentration(MIC)and the minimum bactericidal concentration(MBC)of the extracts on the two bacterial were determined firstly. Then,the biofilm inhibition effect was measured using a microtiter plate assay. The results showed that the anthocyanin extract showed a certain inhibitory effect on both Pseudomonas lundensis and Pseudomonas fluorescens,and the minimum inhibitory concentrations of Pseudomonas lundensis and Pseudomonas fluorescens were 1500 and 1000 mg/mL respectively. At a sub-inhibitory concentration,500 mg/mL of the anthocyanin extract inhibited the biofilm formation of Pseudomonas lundensis and Pseudomonas fluorescens significantly,and reduced bacterial adhesion on the contact surface for the two pseudomonas significantly(p<0.05). The anthocyanin extracts from Rhodomyrtus tomentosa(Ait.)Hassk showed potential value for development as a biofilm inhibitor of Pseudomonas lundensis and Pseudomonas fluorescens.