Herein, a nitrogen-doped graphene (NPGR) with amphiphilic surface was efficiently synthesized by radio-frequency cold plasma under low vacuum, using ammonia as plasma source. NPGR supported platinum nanocatalyst (Pt/NPGR) was then prepared for aqueous-phase hydrogenation of cinnamaldehyde (CAL) and effects of nitrogen doping on the reaction were investigated. Results indicated the formation of a Pickering emulsion catalytic system, exhibiting the high catalytic performance. Apparent initial reaction rate constant (k) over it arrived at 1.07 h−1, higher than that over Pt catalysts supported on pristine graphene (Pt/ GR, 0.62 h−1) and graphene oxide (Pt/GO, 0.15 h−1), respectively. On the other hand, the selectivity to cinnamyl alcohol kept high (84%) at 95% CAL conversion. In addition, the catalyst showed good recyclability for the reaction. The high catalytic performance of Pt/NPGR in aqueous-phase CAL hydrogenation was thanks to the enhanced surface properties of graphene after doping a small amount of nitrogen in it.