A novel FeNi3/SiO2/ZnO magnetic nano-composite was synthesized for the first time and characterized by means of the X-Ray diffraction (XRD), diffuse reflectance spectroscopy (DRS), transmission electron microscope (TEM), field emission scanning electron microscope (FESEM), vibrating sample magnetometer (VSM), and energy dispersive spectroscopy (EDS) techniques. The photocatalytic activity was evaluated by degradation of tetracycline in aqueous suspension under visible light irradiation. The results showed that the complete degradation of tetracycline was attained under specific conditions of pH 9, photocatalyst loading of 0.02 g/L, contact time of 200 min and initial tetracydine concentration of 15 mg/L Under these conditions, the reduction of chemical oxygen demand (COD) and total organic carbon (TOC) were 87.94% and 61.76%, respectively. The reusability test showed that the photocatalyst had negligible efficiency lost (4.04%) after four cycles of tetracycline degradation. Finally, the mechanism of degradation was investigated and reaction products were detected by GC/MS. Our findings pave a new way to facilitate the design of photocatalysts for water treatment. (C) 2020 Published by Elsevier B.V.