Photocatalysts can be effectively recovered and reused by compounding with magnetic nanostructures. How to further improve the photocatalytic performance of magnetic heterojunction photocatalysts remains a great challenge. In this work, g-C₃N₄/ZnFe₂O₄ (CN/ZFO) magnetic heterojunction photocatalyst was first prepared and then modified with ultrathin MoS₂ (CN/ZFO/MoS₂) by simple ball-milling method. Then the photocatalytic removal of Cr(Ⅵ) performance of the prepared series photocatalysts was evaluated in detail. The optimum CN/ZFO/MoS₂ can achieve 99.3% Cr(Ⅵ) removal under 200-min simulated sunlight illumination, which is much higher than CN/ZFO (54.0%). The enhanced photocatalytic performance benefits from the modification of MoS₂, which improves the light absorption performance, facilitates the transfer of photogenerated carriers, increases the concentration of photogenerated carriers and promotes the effective separation of photogenerated carriers. This work provides a theoretical basis for further preparation of magnetic recyclable photocatalysts with high photocatalytic performance.