Herein, ultrafine PtNi nanoparticles (NPs) supported on N-functionalized multi-walled carbon nanotubes (N-MWCNTs) were facilely obtained. The N species on N-MWCNTs not only benefit the formation of PtNi NPs but also accelerate the dehydrogenation of hydrous hydrazine, affording a high turnover frequency of 1595 h-1 with 100% H2 selectivity. In addition, the N species can be used as an "anchor" to stabilize the bimetallic NPs and efficiently restrain the aggregation, giving robust stability of the catalysts for decomposition of hydrous hydrazine over PtNi/N-MWCNTs.