In this work, MoS2-graphenecomposites (MoS2/RGO) were successfully synthesized via hydrolysis of lithiated MoS2 (LiMoS2). The obtained products as well as the photocatalytic activities in the degradation of Rhodamine B(RhB) were characterized by X-ray diffraction, Field Emission scanning electron microscopy, High resolution transmission electron microscopy, Fourier transform infrared spectroscopy, Raman spectroscopy and UV-Vis absorption spectroscopy, respectively. The result shown that MoS2/RGO composite exhibit excellent photocatalytic performance than to Restack MoS2, with nearly 90% of RhB degraded after visible light irradiation for 30 min. This excellent photocatalytic activity could be attributed to the synergistic effect that arises between the MoS2 and RGO, which significantly reduces electron–hole pair recombination. Moreover, the possible photocatalytic mechanism of MoS2/RGO composites was also proposed.