The effects of changes in microbial communities and microbial decomposition of particulate organic matter (POM) during simulated sinking and incubation were inverstigated under progressively increased hydrostatic pressure. DNA-stable isotope probing (SIP) and high-throughput sequencing of 16S rRNA genes showed that 19 OTUs were labelled by ¹³C, and were affiliated mostly with Bacteroidia, α- and γ- Proteobacteria in situ water. The types and abundances of active OTUs in PA or FL faction differ significantly under several pressure gradients. The results revealed the clear compositional differences between the active PAM and FLM communities. Dynamic succession between PAM and FLM occurred with increasing hydrostatic pressure. Microbial network interactions changed dramatically with pressure, dominated by positive interactions at low pressures (0.1, 10 and 30 MPa) and by negative interactions at high pressure (60 MPa), suggesting strong species competition in the deep ocean. The results further showed that microbial communities exhibited clear separation and compartmentalization at high pressure, indicating network resilience and stability. The results significantly expanded the understanding of how pressure during simulated sedimentation affects the community structure and function of microbes associated with the descending particulates in the ocean.