The magnetite/zinc oxide (Fe3O4/ZnO) nanocomposites were synthesized​ by the solid-state method using different ratios of zinc oxide and iron oxide. The structural, morphological, and optical properties of nanocomposites were analysed by X-ray diffraction (XRD), Fourier transform infrared spectra (FT-IR), Raman spectroscopy, transmission electron microscope (TEM), UV–Vis diffuse reflectance spectra (UV–Vis/DRS) and Photoluminescence (PL) spectrophotometry. A significant Raman shift which recorded in nanocomposite due to the ZnO component which is strongly incorporated with the magnetic Fe3O4 nanoparticles. Furthermore, Fe3O4/ZnO has a strongly quenching in PL intensity indicating stability between electrons and holes (e/h). The photocatalytic activities of Fe3O4/ZnO nanocomposites were investigated by the degradation of methylene blue in aqueous solution under visible light in different condition of pH, initial concentration and different trapping agents for free radicals (Tert-butyl alcohol (TBA), p-benzoquinone (BQ) and disodium ethylenediaminetetraacetic acid (Na2-EDTA)). The results revealed that the photodegradation efficiency of ZnO compound with presence of magnetite improved from 13.5% to 88.5%. The optical results show enhancement of nanocomposite absorption under the visible region with a high life time between e/h at the optimum ratio between Fe3O4/ZnO (MZ4), which can applied to obtain high photocatalytic degradation of methylene blue under visible light. Finally, the catalytic activity has been stabled when such photocatalyst was utilized again for several cycles.