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Loading a noble metal on Bi₄Ti₃O₁₂ could enable the formation of the Schottky barrier at the interface between the former and the latter, which causes electrons to be trapped and inhibits the recombination of photoelectrons and photoholes. In this paper, AgPt/Bi₄Ti₃O₁₂ composite photocatalysts were prepared using the photoreduction method, and the effects of the type and content of noble metal on the photocatalytic performance of the catalysts were investigated. The photocatalytic degradation of rhodamine B (RhB) showed that the loading of AgPt bimetallic nanoparticles significantly improved the catalytic performance of Bi₄Ti₃O₁₂. When 0.10 wt% noble metal was loaded, the degradation rate for RhB of Ag_0.7Pt_0.3/Bi₄Ti₃O₁₂ was 0.027 min⁻¹, which was respectively about 2, 1.7 and 3.7 times as that of Ag/Bi₄Ti₃O₁₂, Pt/Bi₃Ti₄O₁₂ and Bi₄Ti₃O_12. The reasons may be attributed as follows: (i) the utilization of visible light was enhanced due to the surface plasmon resonance effect of Ag and Pt in the visible region; (ii) Ag nanoparticles mainly acted as electron acceptors to restrain the recombination of photogenerated electron-hole pairs under visible light irradiation; and (iii) Pt nanoparticles acted as electron cocatalysts to further suppress the recombination of photogenerated electron-hole pairs. The photocatalytic performance of Ag_0.7Pt_0.3/Bi₄Ti₃O₁₂ was superior to that of Ag/Bi₄Ti₃O₁₂ and Pt/Bi₃Ti₄O₁₂ owing to the synergistic effect between Ag and Pt nanoparticles.