Objective: Combining well-seismic data with sedimentary simulations can help clarify the coupling between subaqueous low-relief uplifts and fluvio-tidal interactions in the Pinghu Formation of Xihu Sag. Method: Utilizing well-seismic data, we initially explore the characteristics of complex topography and landforms, as well as tidal action features in the study area. By employing the sedimentary numerical simulation method (Delft3D), an idealized model is established to investigate the coupling relationship features between the subaqueous low uplift and tidal currents in the study area by altering topographic characteristics and tidal amplitude conditions. Results: (1) Influenced by the underwater low-relief topography, the sand bodies in the study area develop large-scale tidal sandbars and extensive sand sheets during the processes of flooding and ebbing tides.(2) Under specific geomorphic features, there is a positive correlation between tidal amplitude and the degree of delta modification, leading to the development of large-scale tidal sandbars, sand sheets, and tidal channels. Under the same tidal amplitude, the underwater low-relief topography forms larger-scale sandbars, sand sheets, and tidal channels compared to barrier island topography. Conclusion: The transformation and evolution of the delta in the study area can be divided into three stages: river-dominated stage, tidal reworking stage, and topography-river-tidal coupling control stage. The coupling effect of complex geomorphology and tidal currents in the study area on the modification of sand bodies is mainly manifested as tidal sandbars and extensive sand sheets on both sides of the tidal channels shaped by underwater low-relief topography. The interaction between this unique geomorphic feature and the fluvio-tidal hydrodynamic forces is significantly distinct from that of barrier island coastal systems, making it more favorable for the formation of large-scale lithologic traps.