In the present study, g-C3N4/Fe3O4/Ag3PO4/AgCl nanocomposites endowed with efficient photocatalytic activity under visible-light irradiation have been successfully prepared by a facile ultrasonic-irradiation method. The prepared samples were characterized by XRD, EDX, AAS, SEM, TEM, UV-vis DRS, FT-IR, TG, PL, and VSM techniques. Rhodamine B, methyl orange, fuchsine, and phenol were selected as pollutants to evaluate photocatalytic activity of the as-prepared samples. Among the samples, the g-C3N4/Fe3O4/Ag3PO4/AgCl (30%) nanocomposite displayed the highest photocatalytic activity. It was found that activity of this nanocomposite in degradation of rhodamine B is nearly 22, 6, and 7.5-times higher than those of the g-C3N4, g-C3N4/Fe3O4/Ag3PO4 (20%), and g-C3N4/Fe3O4/AgCl (30%) samples, respectively. The significant amount of saturation magnetization (8.78emu g(-1))) for this nanocomposite indicated that the photocatalyst can be easily separated from the treated solution using a magnetic field. According to the trapping experiments, it was found that holes are main active species, driving the degradation reaction. This work suggests that the quaternary nanocomposite is promising photocatalyst for degradation of organic pollutants under visible-light illumination. (C) 2016 Elsevier Inc. All rights reserved.