The Dongwan gold deposit, located in the eastern Tongbai-Dabie orogenic belt, is a newly discovered vein-type gold deposit whose metallogenic characteristics remain unclear, limiting the understanding of its gold enrichment mechanisms and processes. This study reveals that the ore bodies are controlled by a NE-trending fault system, and the mineralization can be divided into four stages: quartz–coarse-grained pyrite, gray quartz, quartz–polymetallic sulfides, and quartz–carbonate (S1-S4). The ore fluids belong to a NaCl-H?O±CO? system with moderate-to-low temperatures (114~336 °C) and salinities (1.4 %NaCleqv~16.1 %NaCleqv). The δDV-SMOW values range from -100.0‰ to -64.2‰, and δ1?OH?O values vary between -10.1‰ and 1.0‰. Electron probe microanalysis (EPMA) reveals that visible gold, primarily composed of native gold and electrum, occurs in fractures and intergranular spaces of the S3 pyrite, representing the main occurrence of gold in the deposit. Trace element analysis of pyrite from different stages indicates that invisible gold mainly exists as lattice-bound gold, with strong positive correlations between Au and Ag, as well as Ag and Pb. Except for Py1-1, the δ3?S values of pyrite range from 0.87‰ to 3.34‰, showing an initial increase followed by a decrease from the S1 to S3. Comprehensive analysis suggests that the ore-forming fluids were predominantly magmatic in origin. During the S3, gold-rich fluids superimposed on the system, leading to extensive precipitation of independent gold minerals through fluid immiscibility/boiling conditions. Therefore, although the Dongwan gold deposit is situated near a NW-trending fault zone, the NE-trending ore-controlling structures formed during the Early Cretaceous and the superposition of gold-rich fluids in the main stage are the most critical metallogenic conditions, which are essential for future gold deposit exploration in the region.