The g-C₃N₄/MoS₂ nanosheets were prepared via a facile ball milling method. The composite photocatalysts were characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), UV–vis diffuse reflectance spectroscopy (DRS) and photoluminescence (PL) spectroscopy. The results indicated that MoS₂ nanosheets were successfully coupled into the g- C₃N₄ to form C₃N₄/ MoS₂ heterojunction. The photocatalytic activities were evaluated by degradation of organic Rhodamine B (RhB) under visible light irradiation. The kinetic constant of RhB degradation with g-C₃N₄/MoS₂ nanosheets-2 wt % heterojunction (0.0368 min_?1) is about 4.3 as high as that of the bulk g-C₃N₄ (0.00840 min_?1). The enhanced photocatalytic activities can be mainly ascribed to the efficient separation and transportation of photo-induced electron-hole pairs. The possible photocatalytic mechanism of composites was proposed according to the light trapping experiment.