Several 2. 5D derived structures SiO2f / SiO2 composites were fabricated by sol-gel using warp-laid-in 2. 5D woven structure,z-laid-in 2. 5D woven structure and warp & z-laid-in 2. 5D woven structure. The mechanical properties in the warp direction between these composites and prior 2. 5D SiO2f / SiO2 composite were compared in this paper, and so the effects of the straight warp yarn proportion and fiber volume fraction on the mechanical properties. The fiber reinforcement architecture of warp & Z-laid-in 2. 5D fabric was optimized on this basis. The results show that the mechanical properties of composites in the warp direction have been improved obviously by using warp & Zlaid- in 2. 5D fabric as the reinforcement. While the longitudinal tensile strength remained basically unchanged, the longitudinal compressive strength of the low density composites (1. 6g/ cm3 ) increased by 4. 3 times compared with prior high density 2. 5D composite (1. 65g/ cm3).