To gain further insight into the surface water and groundwater exchange process in typical salt marsh-tidal creek systems in Yancheng City, Jiangsu Province, continuous in-situ monitoring and sampling analysis of data including water volume, salinity, and isotopes were conducted, and the exchange fluxes between surface water and groundwater during both spring and neap tides were estimated, revealing the patterns of surface water and groundwater interactions. Results indicate that tides serve as the primary driving force of surface water and groundwater exchange in the salt marsh-tidal creek systems. The exchange flux is markedly influenced by tidal conditions, with exchange flux during spring tides reaching up to 26-30 times that during the neap tides. During the tidal cycles, surface water recharge and groundwater discharge are almost equivalent. Although the net water flux can be neglected, this process causes a significant discharge of stratum salts, with an average salt flux of up to 140 t/d. Furthermore, a discharge process of deeply trapped marine water with a larger space-time scale exists in the study area, which may have non-negligible impacts on water, salt, and heat exchange.