Cf/C-SiC composites have become the preferred material for high-temperature load-bearing applications because of their low density, high strength, and excellent thermal-physical properties. Due to the composite’s poor sintering performance, the sintering temperature and pressure required for the preparation of Cf/C-SiC by traditional methods are also relatively high, which limits its engineering application. Herein, based on the precursor-derived ceramic route and C/C composites material preparation process, a binary binder (coal pitch and polysilylacetylene) is developed, which combines a carbon source, SiC precursor, and semi-ceramic SiC filler organically. Then, the SiC phase was successfully introduced into C/C composites by the slurry impregnation-hot pressing sintering method. The prepared Cf/C-SiC composites showed good mechanical properties, with a density of 1.53 g/cm³ and a bending strength of 339 ± 21 MPa. Moreover, the effects of the binary binder on the microstructure, density, and mechanical properties of Cf/C-SiC composites were investigated. This work provides a novel and effective approach to fabricating Cf/C-SiC composites with low density and high strength.