Silicon carbide (SiC) fiber–reinforced SiC matrix (SiCf/SiC) composites, employing two SiC fibers, KD-I and KD-II, respectively, were fabricated by the precursor infiltration and pyrolysis process. A pyrocarbon coating was used as the fiber-matrix interface. In addition, the effects of heat treatment on the properties of the SiC fibers and SiCf/SiC composites were investigated. Results revealed marginal performance degradation of the KD-I and KD-II SiC fibers after heat treatment at 1100°C for 1 h. However, heat treatment at 1400°C for 1 h led to the decrease in the single-filament tensile strength of the KD-I and KD-II SiC fibers by 50.2% and 10.1%, respectively. In addition, the flexural strength of the SiCf/SiC composites, which were fabricated using the KD-I and KD-II SiC fibers, decreased by 49.6% and 15.9%, respectively. The difference in the composition of the KD-I and KD-II SiC fibers demonstrated that the SiC fibers and SiCf/SiC composites decreased by varying degrees.