Abstract: Marine subsurface positioning, navigation and timing (PNT) faces a series of scientific and tech⁃ nical challenges, including: characterization and modeling of marine environment and acoustic observation errors, dynamic evolution of seafloor geodetic datum, and optimal multi-sensor information fusion and re⁃ silient navigation. This paper summarizes recent progresses by Chinese scholars in marine PNT theories and technologies. Key advancements reviewed include: (1) Ocean sound speed field characterization and acoustic observation environmental error compensation.(2) Seafloor geodetic network observation, time-se⁃ ries fusion processing, and dynamic datum maintenance. (3)Multi-frequency multi-mode acoustic naviga⁃ tion and environmental information augmented navigation, sonar/ inertial navigation system / pressure sen⁃ sor/Doppler velocity log/gravity-magnetic terrain matching etc. Furthermore, the main challenges and fu⁃ ture directions for seafloor geodetic datums and navigation are generalized. This study aims to further ex⁃ plore and discuss refined marine PNT theories and technologies, and to provide a reference for in-depth re⁃ search and engineering applications of PNT in China.