MgFe2O4/ZnO magnetic nanocomposite materials was prepared by hydrothermal method, and the narrow band gap MgFe2O4magnetic semiconductor is matched with the wide band gap ZnO semiconductor to form a composite photocatalyst with heterojunction. The composites were characterized by X-ray diffraction (XRD), Scanning electron microscope(SEM), Vibration sample magnetic field meter(VSM), and UV- visible diffuse reflectance spectroscope (UV-Vis DRS), meaning to analysis its surface structure, morphology, magnetic properties and photocatalytic activity. Results show that the introduction of MgFe2O4 effectively extend the absorption range, thereby enhance the ZnO photodegradation efficiency of pollutant improves the adsorption capacity and photocatalytic activity of composites. The photodegradation efficiencies of MO are approximately 95.2% after 60 min under visible light. After 5 cycles recovery tests, its photocatalytic degradation of methyl orange is still above 87.3%.