In this study, a new magnetically separable Cu2ZnSnS4/ZnFe2O4 p-n heterostructured nano-photocatalyst was first prepared by a facile two-step hydrothermal method. The characterizations of morphology and microstructure revealed that the p-type Cu2ZnSnS4 (CZTS) nanosheets were successfully assembled on the surface of ZnFe2O4 (ZFO) nanospheres, forming a CZTS/ZFO p-n heterostructures. A series of test results showed that this p-n heterostructures could not only efficiently expand spectral response and promote photoinduced charges separation, but also increase the specific surface areas for photocatalytic and photo-Fenton reactions. All these factors resulted in the p-n heterostructured CZTS/ZFO nano-photocatalyst plus H2O2 having a significantly enhanced photocatalytic activity for degradation of methyl orange (MO) at visible light irradiation, compared to the pure ZFO, the removal efficiency available reached up to 91% within120 min. These outstanding performances should be ascribed to the synergistic enhancement effects of the CZTS/ZFO p-n heterostructure combining with photo-Fenton mechanism, which could be confirmed by exploring the dominant effects of radical scavengers and the yield of hydroxyl radicals (center dot OH) on the surface of the p-n heterostructured nano-photocatalyst with and without contribution of photo-Fenton reaction for the MO removal. Furthermore, the CZTS/ZFO p-n heterostructured nano-photocatalyst exhibited remarkably stable and easy separated performances, suggesting a promising application for the photo-oxidative degradation of organic contaminants.