The Cr₇C₃-CrSi₂-Al₂O₃ composite coatings were prepared by plasma spraying Cr₇C₃-CrSi₂-Al₂O₃ and Al-Cr₂O₃-SiC composite powders, respectively. The microstructure, formation mechanism and properties of the two Cr₇C₃-CrSi₂-Al₂O₃ composite coatings obtained by plasma spraying were investigated, and the reaction mechanism of the Al-Cr₂O₃-SiC system was explored. The results show that the coating obtained by plasma spraying Al-Cr₂O₃-SiC composite powders had thinner lamella and more tortuous interlayer interface, and the in-situ synthesized Cr₇C₃, CrSi₂ and Al₂O₃ in the coating were all nano-crystallines. Compared with the Cr₇C₃-CrSi₂-Al₂O₃ coating prepared by plasma spraying Cr₇C₃-CrSi₂-Al₂O₃ composite powders, the plasma-sprayed Cr₇C₃-CrSi₂-Al₂O₃ coating obtained from Al-Cr₂O₃-SiC composite powders had higher density, higher microhardness (increased by 20%), better fracture toughness and lower wear rate (reduced by 28%).