The work aims to study effects of Nano-WC on abrasive wear resistance of Ni-based alloy spray-melted coating. Microstructure and phase structure of Ni-based alloy spray-melted in oxyacetylene flame as well as WC-reinforced Ni-based alloy spray-melted coatings of two different structures were analyzed using scanning electron microscopy (SEM) and X-ray diffractometer (XRD). Meanwhile, wear resistance of the three coatings was tested using abrasive wear testbed. Addition of nano-WC powder could effectively improve macro hardness of spray-melted coating. Nano-WC reinforced Ni-based alloy spray-melted coatings contained not only γ-(Ni, Cr) solid solutions, Cr carbide, boride and micro-scale WC particles, but also a certain amount of nano-WC particles and a small amount of high-hardness W2C phase. The results of abrasive test showed that wear weight loss of nano WC-reinforced layer was 56% of that of NiWC35 coating and 73% of that of Ni60. Compared with surface microstructure of the worn coating, nano-WC particles in the coating could effectively reduce depth of abrasive particles impressed into the spray-melted layer, so as to control ploughing amount of the abrasive particles on the spraying layer. Generally, the by γ-(Ni,Cr) solid solutions, Cr23C6, Cr7C3, Cr3Ni2, unmelted WC particles and hardness phases such as W2C formed by WC decarburization in the nano WC-reinforced Ni-based alloy spray-melted coating can greatly improve hardness and abrasive wear resistance of the coating.