To prevent the strong interfacial reactions in SiC fiber reinforced nickel-based superalloys matrix composites, yttrium oxide (Y2O3) was used as the barrier coating by reaction magnetron sputtering method. Compared with the composites without coating, after the high temperature hot isostatic pressing (HIP), Y2O3 coating effectively protected the SiC fibers from the interfacial reactions, and no element diffusion can be observed between the fibers and the matrix. The elevated temperature tensile tests were performed on both SiC/GH4738 and SiC/Y2O3/GH4738 composite. The results indicated that the strength of the composites with Y2O3 coating can increase about 35% in comparison with the composites without coating.