Mill concentrates of ore sulfides from three magmatic-hydrotherml ore deposits were stud- ied for δ 34 S at the granite-hosted Xihuashan deposits, and carbonate-hosted Shizhuan and Huashaping deposits. These ore deposits occur in the South China Fold System, which is composed of mid-Paleo- zoic miogeosynclinal sediments dominant in carbonates toward the Devonian age. Averages of the ore sulfides are -0.9 permil for the Xihuashan, +7.0 permil for the Shizhuan and +13.2 permil for the Huashaping deposits. Endogranitic ore sulfur of the Xihuashan and the Shizhuan deposits are consid- ered magmatic, derived from by ca.+2 ‰ δ 34 S granitic magma, but the carbonate-hosted ore sulfurs at the major part of the Shizhuan and Huashaping deposits are much higher than those expected from rock sulfur δ 34 S values of the Yanshanian granites of the South China Fold System. Thus, addition of 34 S-enriched sulfur into the ore solutions is considered. Devonian and Carboniferous carbonates of the South China Fold System are very high in the δ 34 S values of structurally substituted sulfate (SSS) sulfur, averaged as +25.7 and +15.7 permil, respec- tively, which are higher than the reported values from other areas of these ages. The SSS contents of the Paleozoic carbonates are very low at present, but recent carbonates contain typically 0.1 to 1 % equivalent sulfate. The very low SSS contents in the wall rock carbonates and high δ 34 S values in the ore sulfides may have been resulted from carbonate SSS extracted during recrystallization and some- how mixed with magmatic ore fluids when the granitic magmas intruded, then precipitated as the ore sulfides.