Microorganisms play an important role in the circulation of phosphorus (P) in the sediment of coastal wetland ecosystems. In this study, solution 31P nuclear magnetic resonance (NMR) was used to determine different forms of P in the sediments of four different seagrass meadows and a bare tidal flat, while high-throughput 16S and ITS rRNA gene sequencing was used to determine the microbial community composition. The solution 31P-NMR spectra revealed six forms of the P compounds detected by the NaOH-EDTA extraction of sediments, where Ortho-P was the most dominant P compound, followed by Mono-P. The Po compounds were more varied in the seagrass meadow sediments and more abundant compared to the bare tidal flat. Bacterial communities in the sediments collected from