The electrochemical performance of layered O3-type NaCrO₂ cathode material is significantly affected by the side reactions between NaCrO₂ and electrolyte during sodium storage. A uniform Cr₂O₃ coating layer was in situ constructed on the surface of NaCrO₂ by controlling the excess ratio of sodium source. The structure, morphology, valence and electrochemical performance of the Cr₂O₃-coated NaCrO₂ were characterized. The results indicate that the Cr₂O₃ coating layer does not alter the crystal structure and morphology of NaCrO₂, but effectively suppresses the side reactions between NaCrO₂ and electrolyte, and improves the surface/interfacial stability of NaCrO₂ material. The Cr₂O₃-coated NaCrO₂ exhibits improved electrochemical performance with a capacity retention of 66.4% after 500 cycles at 10C.