Abstract: This paper focused on the hot issue of quorum sensing regulatory function of marine bacteria. The influence of the quorum sensing system of the phycospheric Sulfitobacter pseudonitzschiae H46 on its ecological function and algae inhibition was studied and algal-bacterial interaction modulated by quorum sensing was explored. H46 was co-cultured with different concentrations of quorum sensing inhibitor (β-cyclodextrin). Then the functions of biofilm formation, DMSP degradation and algicidal activity of H46 were analyzed. And the potential regulation function of H46 quorum sensing system was confirmed. The results showed that the induced activity of the quorum sensing signaling molecule AHLs of H46 was partially quenched by β-CD. And then the biological ability of membrane forming, DMSP degradation and alga-inhibit of H46 were inhibited. In this paper, we explore the inhibitory effect of bacteria on the growth of microalgae, which provides a new perspective for the study of mechanism of algal-bacterial interaction.