The impact of nano-structured WC particles on the mechanical and frictional properties of 18Ni300 maraging steel has been studied by molecular dynamics simulations and experiments. The result shows that the melting temperature of the nano-WC particles increased with their size and tended to be similar to the melting temperature of bulk materials. The mechanical properties of nano-WC-reinforced 18Ni300 steel increased by 6 GPa 700 K compared with that of normal WC-reinforced 18Ni300. Moreover, after the doping of 6% WC, the friction coefficient of Fe–6%WC decreased by 30.7% relative to that of Fe. Cladding layers of 6% WC ceramic-reinforced 18Ni300 and unreinforced 18Ni300 were prepared by using transferred arc welding. The results of experiments showed that the friction coefficient of the 6% WC ceramic-reinforced 18Ni300 decreased by 18.6% relative to that of unreinforced 18Ni300. This shows that the addition of nano-WC improved the frictional properties of 18Ni300, and corroborates the results of the simulations. The results provided here can be used to guide the preparation of nano-WC-reinforced 18Ni300 maraging steel with excellent wear resistance.