Abstract: Ni-based alloy coatingswith nano micro-Sm₂O₃ particles addition produced by a 5 kW CO₂ laser on Q235 low carbon steel were introduced.Cross-section of the coatings was examined to reveal their microstructure using optical microscope, scanning electron microscope, and X-ray diffractioninstrument.The hardness and wear resistance were measuredwith microhardness tester and MM200 type sliding wear machine.The results showed that γ-Ni and Cr₂₃C₆ exist inthe coatings.Fe₇Sm, Ni₃Si and Ni₃B are also foundby adding nano-Sm₂O₃.Fine microstructure and equiaxed dendrite are observed with nano-Sm₂O₃ addition.A thin layer ofmetallurgical bonding, the white and bright strip, is observed by adding the rare earth oxide.The hardness and wear resistance of the coatings with nanoSm₂O₃ addition are better than that with micro-Sm₂O₃.The mechanism was found from abrasive adhesive wear to fretting wear.