MoS2 and its derivates have been regarded as a promising catalyst for the hydrogen evolution reaction (HER), and their edge sulfur sites are key factors for the HER performance. Here, we develop a facile strategy to grow nonstoichiometric molybdenum sulfide (MoSx) with more active sulfur sites on porous N-doped graphene (MoSx@CN). Experiments demonstrate that the introduction of porous N-doped graphene not only facilitates the fast transfer of charge and the efficient infiltration of the electrolyte but the N dopants could be used as the nucleation sites for MoSx to possess more active bridging S-2(2-) sites. Consequently, the obtained MoSx@CN catalyst possesses an outstanding HER activity, which shows an overpotential of 256 mV at 100 mA cm(-2) with a Tafel slope of 49 mV dec(-1). This study provides a new strategy to optimize transition metal dichalcogenide-based catalysts for energy-related applications.