Ag₃PO₄/sulfur-doped g-C₃N₄ heterojunctions were fabricated by the means of a facile calcination and co-precipitation method. Structural characterization suggested that Ag₃PO₄ was successfully loaded onto sulfur-doped g-C₃N₄. The absorption band edges of sulfur-doped g-C₃N₄ were shifted to the longer wavelength in comparison with bulk g-C₃N₄. The Ag₃PO₄/sulfur-doped g-C₃N₄ heterojunctions manifested substantially higher visible-light photocatalytic performance as compared with Ag₃PO₄/bulk g-C₃N₄. Photoluminescence spectra suggested that the stable Ag₃PO₄/SGCN heterojunctions could effectively address the electron-hole recombination rate, together with remarkably enhancing the photocatalytic activity. The enhancement of light absorption and better dispersion in Ag₃PO₄/sulfur-doped g-C₃N₄ provide more migration channels, together with posing crucial responsibility for the enhanced photocatalytic performance.