Environmental barrier coatings (EBCs) are expected to be applied to the hot-section components of a new generation of high thrust-to-weight ratio aero-engines. Rare-earth silicates have been acknowledged as promising alternatives to EBC materials due to their superior high-temperature phase stability, suitable coefficient of thermal expansion, and long durability in water vapor. However, the calcium-magnesium-alumino-silicates (CMAS) molten salt corrosion under service conditions has become a bottleneck that limits the application of rare-earth silicates in EBCs. Factors such as the composition of CMAS and the crystal structures of rare-earth silicates have a significant impact on their corrosion behavior. In this paper, X1-Gd₂SiO₅ and X2-RE₂SiO₅ (RE=Y, Er) coatings with different crystal structures, were prepared by atmospheric plasma spraying (APS) technique. Their corrosion behaviors and mechanisms of the three kinds of coatings under CMAS melt environment at 1400 ℃ were explored. Results showed that the corrosion resistance of X2-RE₂SiO₅ coatings were better than that of X1-Gd₂SiO₅ coating due to their phase compositions and stability of crystal structure. After corrosion by CMAS, X1-Gd₂SiO₅ coating dissolved in CMAS melt and formed apatite phase, while the X2-RE₂SiO₅ coatings not only formed apatite phase, but also formed garnet phase from reaction of the RE₂O₃ in the coatings with Al₂O₃ in CMAS. Formation of generate garnet phase could increase relative content of CaO and SiO₂ in CMAS, and promote formation of dense apatite layer, thereby improving corrosion resistance. This study provides a strategy for designing EBC systems with excellent CMAS corrosion resistance.