Abstract: Through the study of H-O-C-S isotopic data for rock (mine) stones from Laowangzhai gold deposit，the characteristics of hydrogen-oxygen isotopic compositions indicated that water in ore-forming fluid is the mixed magmatic water.Both carbon and sulfur isotopic compositions have clearly mantle-derived characteristics.From what has been discussed above，the ore-forming fluids of Laowangzhai gold deposit mainly derives from deep mantle，and their properties are transformed from magma fluids to hydrothermal fluids in the course of metasomatism and alteration，which leads to crust-mantle mixing simultaneously to be in favor of mineralization.

Key words: Hydrogen-oxygen isotope, Carbon isotope, Sulfur isotope, Deep ore-forming fluids, Laowangzhai gold deposit