Abstract: The Lishui-Jiaojiang Sag, a Paleocene rift basin, exhibits significant variability in reservoir quality across different depositional systems under multiple provenances. To elucidate reservoir characteristics of various depositional systems and identify favorable exploration prospects, this study integrates data from cores, well logs, seismic surveys, and laboratory analyses to identify various depositional systems and compare reservoir quality under similar sandstone types and burial depths. The study suggests that the Lishui Sub-sag B developed two depositional systems: shallow-marine submarine fans and sand bars, both sourced from the southern Zhemin Uplift. The sandstone types are predominantly litharenite rich in volcanic lithics. At similar burial depths, sand bars, subjected to strong hydrodynamic conditions and repeated winnowing, exhibit better grain roundness and sorting, along with lower content of plastic volcanic lithics, resulting in superior reservoir quality compared to submarine fans. In the Lishui Sub-sag A, Sub-sag C, and Jiaojiang Sag, braided delta and fan delta depositional systems are developed, sourced from the northern Zhemin Uplift and the Yandang Uplift. The reservoirs are characterized by relatively high porosity and permeability, owing to higher contents of metamorphic lithics and felsic minerals which resistant to mechanical compaction. Under similar burial depths, the reservoir quality of conglomerates and coarse sandstone in the proximal braided delta fronts and fan delta fronts is significantly better than that of fine sandstone in distal delta front settings. Grain size is the primary controlling factor for high-quality reservoirs in this region. Therefore, it is recommended that in the Lishui Sub-sag B, priority exploration be directed toward sand bars and amalgamated channels and channelized lobes in proximal submarine fans with relatively high maturity. In the Lishui Sub-sag A, Sub-sag C, and Jiaojiang Sag, the proximal delta front areas, along with distal high-energy coarse-grained ‘sweet spots’, exhibit superior reservoir quality and hold promising exploration potential.