[Background] Quorum sensing refers to the phenomenon that bacteria use secreted signal molecules to communicate with each other, while quorum quenching refers to inhibiting the quorum sensing pathway by interfering with the production, release, accumulation or response of signal molecules. [Objective] To explore the diversity of quorum sensing and quorum quenching bacteria in sediment biofilm of Qingdao offshore. [Methods] Culturable bacteria were isolated from the sediment biofilm of Qingdao offshore by marine agar 2216E. The bacteria with quorum sensing and quorum quenching activities were screened by plate interaction and high-throughput screening methods. [Results] A total of 83 bacterial strains and 54 bacterial species were isolated, belonging to the four major phyla of bacteria: Proteobacteria, Bacteroidetes, Firmicutes and Actinobacteria. Among them, 38 strains (45.8%) produced acyl-homoserine lactones signal molecules (AHLs), belonging to Proteobacteria (37 strains, 15 species) and Bacteroidetes (1 strain, 1 species). The dominant bacteria belong to the genera Vibrio and Ruegeria. 57 strains (68.7%) can degrade AHLs, including Proteobacteria (41 strains, 23 species), Bacteroidetes (14 strains, 10 species), Firmicutes (5 strains, 5 species) and Actinobacteria (1 strain, 1 species), which showed high abundance and diversity. [Conclusion] The results of this study indicate that among the bacterial isolates from sediments biofilm in Qingdao offshore, quorum sensing and quorum quenching bacteria showed a high abundance and diversity. It laid a foundation for further research and development.