Zinc ferrite/multi-walled carbon nanotubes (ZnFe 2 O 4 /MWCNTs) composite was prepared by a hydrothermal process and characterized by X-ray diffraction, transmission electron microscopy, and ultraviolet–visible diffusion reflectance spectroscopy. Compared with pure ZnFe 2 O 4 , the ZnFe 2 O 4 /MWCNTs composite exhibits stronger absorption in visible-light range and higher photocatalytic activity, with 99% degradation ratio of methylene blue after 6h visible-light irradiation in the presence of H 2 O 2 . The enhanced photocatalytic activity is attributed to the strong interaction between ZnFe 2 O 4 and MWCNTs which inhibits the recombination of photo-generated charge carriers, and the formation of highly active species OH on the surface of MWCNTs. Therefore, more radicals are formed for degradation of the dye. The enhancing mechanism of the photocatalytic activity of ZnFe 2 O 4 in the presence of MWCNTs is also discussed.