Abstract: B₄C-SiC composite ceramics combine the properties of boron carbide (B₄C) and silicon carbide (SiC) and have good physical and mechanical properties. Compared with monolithic B₄C ceramics, B₄C-SiC composite ceramics have improved fracture toughness. Compared with monolithic SiC ceramics, B₄C-SiC composite ceramics possess increased hardness. B₄C-SiC composite ceramics are expected to replace monolithic B₄C ceramics and monolithic SiC ceramics to be widely used in engineering fields. The mechanical properties of B₄C-SiC composite ceramics are related to the particle dispersion uniformity of B₄C-SiC composite powders. Meanwhile, the mechanical properties of B₄C-SiC composite ceramics are also influenced by their microstructure and phase composition. In order to reduce the sintering temperature of B₄C-SiC composite ceramics, sintering additives are often added to the raw materials. The commonly used sintering additives include carbon, oxides, borides, carbides, metallic elements, and non-metallic elements (excluding carbon). The mechanisms by which different sintering additives promote the sintering of B₄C-SiC composite ceramics vary. At the same time, these sintering additives affect the microstructure of B₄C-SiC composite ceramics, which in turn affects their mechanical properties. Based on the research results of mechanical properties of B₄C-SiC composite ceramics in recent years, the influencing factors of mechanical properties of B₄C-SiC composite ceramics are summarized in this review from the aspects of B₄C-SiC composite powders, microstructure, phase composition, and sintering additives, so as to provide a basis for the design and investigation of B₄C-SiC composite ceramics.