Abstract: Reconstruction of paleosalinity during the Last Glacial Maximum (LGM) is pivotal to understand ocean circulation and global climate change. However, the paleosalinity reconstruction in deep ocean is a challenge due to the lack of reliable proxies. Recently, deep ocean LGM salinities have been reconstructed through simulating pore water chloride ion concentration (Cl⁻) profiles within upper sediments evolving with time based on one-dimensional diffusion-advection, which is a breakthrough for paleosalinity reconstruction. Here we reviewed progresses and applications of this study in details. First, modelling methods especially the key parameters: porosity, effective diffusion coefficient, and advection rate were specified, and the uncertainties and affecting factors of modelling were discussed. Secondly, reconstructed results demonstrate that the LGM deep-water salinity in the Southern Ocean significantly exceeded that of the North Atlantic, which enhanced the northward expansion of Antarctic Bottom Water. Moreover, the LGM salinity gradients within the deep Pacific basin confirm that the deep Pacific LGM circulation pathways are consistent with the modern configuration. The reconstructed deep ocean LGM salinities not only validate the reliability of paleoceanographic circulation models but also provide critical constraints on quantifying glacial meridional overturning circulation intensity and deep-water transport volume. Future studies should extend this modelling to the salinity reconstructions for intermediate waters and marginal seas, and more studies should be carried out in the deep Southern Ocean and northwest Pacific, to obtain deep insights into linkage between ocean circulation and climate change.