Plasma transferred arc welding is a kind of surface modification technology. Plasma transferred arc is used as a heat source and alloy powder is sprayed on the surface of metal materials to prepare a wear-resistant coating with excellent performance. In order to further improve the wear resistance of Fe-based alloy, hard particles are often used as the reinforcements of composite materials. At present, there are few researches on in-situ formed NbC reinforcements in Fe-based alloy coatings, and the density of NbC is very close to that of Fe-based alloy, which can be very evenly distributed in the coatings. In this work, Fe-based alloy coatings without nano-Nb and with mass fraction of 1wt%, 3wt% and 5wt% nano-Nb powder were prepared on Q235 surface by plasma transferred arc welding. The phase composition, microstructure, microanalysis and worn surface observation of the coatings were investigated by means of optical microscope (OM), scanning electron microscope (SEM), energy dispersive spectrometer (EDS) and X-ray diffraction (XRD), respectively. The microhardness and wear resistance of the coatings were tested using microhardness tester and pin-on-disc wear machine. The results showed that the main phases of Fe-based alloy coatings were composed of α-Fe, γ-Fe and Cr7C3. NbC phase was identified in the coating by adding nano-Nb powder, and Cr23C6 phase appeared with addition of 5wt% nano-Nb. The untransformed γ-Fe increased and the microstructure changed from approximately equiaxed microstructure to dendrite with addition of nano powder, and the greatly refined microstructure was obtained by adding 5wt% additive. The microhardness of coatings was improved, which was about 766 HV0.3 increased by about 250 HV0.3 with 1wt% and 3wt% nano-Nb. The wear resistance of coatings was also improved. The minimum friction coefficient of 0.48 was obtained by adding 3wt% nano-Nb. The wear mechanism changed from adhesive wear to abrasive wear.