Ag-loaded n-type Sr₂TiO₄ and p-type Bi₅O₇I heterostructure photocatalyst was prepared in this work. Scanning electron microscopy, UV-Vis optical absorption spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy were performed. Bismuth ions are easily to substitute on titanium sites by adjusting the pH value because Sr₂TiO₄ and Bi₅O₇I exhibit identical orthorhombic layered structure, thus shifting the optical absorption edge of the Bi₅O₇I/Sr₂TiO₄ composite toward long wavelength region and reducing the band gap energy. After Ag loading as a cocatalyst, Ag-Bi₅O₇I/Sr₂TiO₄ composite showed high photocatalytic activity to degrade methyl orange dye under visible light irradiation. This result can be attributed to the high electron-hole separation resulting from the strong electron-withdrawing ability of Ag and the p-n junction formed at the Bi₅O₇I/Sr₂TiO₄ interface. In summary, a facile Ag-loaded Bi₅O₇I/Sr₂TiO₄ heterojunction presented an improved photocatalytic activity and can be served as a promising photocatalyst.