Environmental barrier coatings (EBCs) play a critical role in mitigating the degradation of SiC_f/SiC ceramic matrix composites (CMCs) in complex combustion environment, and improve the service life of thermal engine components. In this paper, by adjusting the parameters of atmospheric plasma spraying (APS), the spraying process of ytterbium disilicate (Yb₂Si₂O₇) under a lower power has been optimized. A two-layer EBC system consisting of ytterbium disilicate and silicon is prepared on the SiC_f/SiC composite substrate by using optimized technological parameters. The thermal resistance and water oxygen corrosion resistance of such two-layer EBC system are investigated. The results indicate that the current ytterbium disilicate/silicon EBC system exhibits good phase stability, excellent water vapor and oxygen corrosion resistance. However, the exposed silicon bonding layer tends to generate an excessive thermal growth oxide (TGO) layer known as SiO₂, leading to an early spallation of the coating.