To improve the high-temperature resistance of the key hot-end parts of the steam turbine, NiCoCrAlY coatings were depositedon a 304 stainless steel substrate by laser cladding. The microstructure and high-temperature oxidation behavior of theNiCoCrAlY coatings were analyzed. The results showed that the NiCoCrAlY coatings contained γ/γ′ and β phases, and themicrostructure was mainly composed of elongated columnar crystals. In addition, after 100 h of oxidation at three differentoxidation temperatures (750, 850 and 950 °C), the coatings showed a relatively low oxidation rate, which was approximatelya quarter of the oxidation rate of the substrate. At the same time, the protective Cr2O3scales were formed on the coatingsurface. When the oxidation temperature was 850 °C, the FeCr2O4spinel formed and internal oxidation zone appeared,when the oxidation temperature reached 950 °C, the FeCr2O4spinel gathered in the local area on the surface of the Cr2O3scale and the internal oxidation was aggravated. In other words, as the oxidation temperature increased, the Fe element inthe matrix formed the FeCr2O4spinel, which accelerated the consumption of Cr element in the coatings and reduced theoverall oxidation resistance of the NiCoCrAlY coatings.