Zn-doped Fe3O4 has been employed as a catalyst for the photo-Fenton process. At the present study, the influence of Zn content in the Zn-doped Fe3O4 on the catalytic activity for the photo-Fenton process was studied. Monodispersed ZnxFe3−xO4 particles were facilely synthesized with higher surface area and several nm of diameter, where x=0, 0.4 and 1.0. Rhodamine B (Rh B), as one of the positive dyes, was selected as a model pollutant. The decolorization efficiency of the Fe3O4 (x=0) for Rh B reached about 90% in 120min under visible light. The Zn content increase in the Zn-doped Fe3O4 inhibited the Fenton process. The higher molar ratio of Fe2+ to Fe3+, smaller band-gap, and more negative zeta potential of the Fe3O4 induced the most excellent photo-Fenton performance for the Rh B degradation.