Abstract: The low-salt fermented shrimp pastes with 10% (w/w) salt addition were made using acetes chinensis as the substrates and Bacillus amyloliquefaciens Y11 and Bacillus velezensis Y12 as fermentation starter cultures to investigate the impact of Bacillus amyloliquefaciens Y11 and Bacillus velezensis Y12 on the quality and bacterial community diversity. Sensory evaluation, flavor analysis, MDA content, TVB-N value, and bacterial community were examined to compare the quality and microbial diversity changes of shrimp paste fermented using single-strain and mixed-strain fermentation methods. The results revealed that shrimp paste subjected to mixed-strain fermentation using two Bacillus strains exhibited higher sensory evaluation scores, color, and flavor assessment than the single-strain and natural fermentation shrimp paste. For the shrimp paste fermented with mixed Bacillus strains, the pH was between 7.5 and 8.0, and remained relatively stable throughout the fermentation process. The MDA content decreased from 0.98 mg/kg to 0.33 mg/kg with an increased fermentation time, and the lowest TVB-N value (33.32 mg/100 g) was observed after 10 days of fermentation. Amplicon sequencing of the fermented shrimp paste indicated the addition of starter cultures had a significant impact on the relative abundance of bacterial communities in the early stage of fermentation. At the end of fermentation, the relative abundance of Alkalibacterium, Atopistipes, Staphylococcus, and Tetragonococcus was relatively high in different groups. These findings provide a theoretical foundation for utilizing Bacillus strains as fermentation agents in producing shrimp paste and other related seafood products.