The Yindongpo gold deposit is situated in an upper Palaeozoic carbon-silicon-mud formation. The pyrite typomorphic mineral shows a transitional attribute between the sedimentary origin and the hydrothermal origin. REE patterns assume gentle inclination towards the right without Eu anomalies. REE of ores and Liangwan granite have close relationship in sources. Sulphur isotope δ³⁴S is 3.1%, with high homogenization. Ores and wall rocks have similar lead isotope composition. They were derived from partial melting of South Qinling continent crust which subducted under North Qinling block. Compositions of radon and hydrogen isotopes indicate that ore-forming fluids came from joint evolution of meteoric, magmatic and metamorphic water. Mineralization has experienced three stages, namely, the formation of original sedimentary mineral source bed, the low-grade metamorphism and the preliminary enrichment of ore-forming elements, and the locating of ore-forming elements derived from mixed hydrothermal water.