Introducing the in-situ reaction synthesis into the thermal spraying process, the content of each phase in the raw material will directly affect the phase and microstructure of the coating obtained by spraying. Therefore, composite powders with different Cr2O3–SiC–Al mass ratios were used as coating materials, and composite coatings were prepared using an atmospheric plasma spraying process. By analyzing the coatings' phase composition, microstructure, wear resistance, and other properties, the effect of the variation of Cr2O3 content in the composite powders on the performance of the coating was investigated. The results showed that with the decrease of Cr2O3 content in the composite powder, the coatings’ compactness, microstructure uniformity, and wear resistance decreased. The coating prepared by Cr2O3–SiC–Al composite powder with a mass ratio of 65:12:23 had good compactness and microstructure uniformity, the microhardness and toughness were also the best among the three groups of coatings, and it presented higher wear resistance.