A small amount of polyvinyl alcohol (PVA) was adsorbed on the surface of the prepared silver phosphate, and the DPVA/Ag3PO4 composite was prepared by heat treatment. The DPVA/Ag3PO4 composite was characterized and analyzed by Fourier transform infrared spectroscopy (FT-IR) and fluorescence spectroscopy (PL). Analysis shows that the conjugate structure exists in DPVA/Ag3PO4 composite particles modified by polyvinyl alcohol composite, the recombination rate of photo-generated electron-hole pairs reduces, and the photocatalytic activity is significantly improved. The visible-light photocatalytic activity of the composite photocatalyst prepared under different conditions (including compound ratio, temperature and time of heat treatment) for the degradation of Methyl orange under visible light was studied. The results show that the obtained DPVA/Ag3PO4 composite materials showed optimal photocatalytic activities when the mass proportion of PVA and silver phosphate was 1∶4000, heated at 190 ℃ for 1 h.