The Laowan gold deposit is one of the typical shear zone type gold deposits in Tongbai area, Henan Province. The characteristics of fluid inclusions suggest that the ore-forming fluid is a K⁺_Na⁺-Cl^-SO₄^2- system which indicates medium-low temperature, low-salinity and CO₂-containing nature. The study of hydrogen oxygen isotopes shows that, in the early stage of the deposit, magmatic water was dominant, and in the late stage, meteoric water was the dominant one. The authors thus hold that the Pb source of the deposit was related to the Guishan Formation Complex and the Laowan granite, and was close to the granite, showing its deep source characteristics. These results provide evidence for the magmatic origin of the ore-forming fluids.