Abundant Neoproterozoic magmatic rocks were emplaced in western Yangtze Block, which are important for reconstructing the Rodinia supercontinent. In this paper, new petrologic, lithogeochemical and geochronological studies of the Eshan granodiorites and porphyritic biotite monzogranites were conducted to explore their origin and geodynamic implications. The porphyritic biotite monzogranites were emplaced at 826.6±2.5 Ma, while the granodiorites have younger crystallization age of 818.3±2.8 Ma. Relative to the porphyritic biotite monzogranites, the granodiorites exhibit lower SiO₂ but higher Al₂O₃, MgO, Fe₂O₃, TiO₂ and P₂O₅ values. In chondrite-normalized REE patterns and trace element spider diagram, both lithologies are enriched in LREEs; compared with HREEs, they have negative Eu anomalies and are depleted in HFSEs relative to LILEs. The porphyritic biotite monzogranites have enriched Nd isotopic compositions, consistent with those of the granodiorites. The geochemical data indicate that the porphyritic biotite monzogranites are likely to have been derived by partial melting of meta-igneous rocks, leaving a granulite source at ca. 826 Ma and subsequent partial melting of the granulite at ca. 818 Ma, thus producing the Eshan granodiorites with A-type affinities. Combined with data available, the results obtained by the authors reveal that the western Yangtze Block was an active continental margin and the South China Block occupied an external location rather than an internal location within the Neoproterozoic Rodinia.