RGO-Fe3O4-Ag3PO4 composite (RFA-Cs) photocatalyst was prepared by a facile and effective electrostatic self-assembly method for photodegradation of Rhodamine B (RhB) under visible light irradiation. The prepared composites were fully characterized by scanning electron microscopy (SEM), X-ray diffraction meter (XRD), UV-vis diffuse reflectance spectroscopy (UV-vis), Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS), photoluminescence spectroscopy (PL) and electrochemical impedance spectroscopy (EIS). The RFA-Cs exhibit extremely high photocatalytic activity and better re-usability. The photocatalytic conversion of RhB reaches as high as 100% after 2 min of light irradiation. A possible photocatalytic degradation and charge separation mechanism were suggested based on the PL spectra and the active species trapping experiments.