A sol-gel-processed mullite powder and Si-Ti-C-O fiber woven fabrics were formed into laminated composites by filtration or doctor blade method using aqueous mullite suspensions containing polyacrylic ammonium (PAA) and methyl cellulose (MC) at pH 8 5. The laminate green composites with 6 and 10 vol% fabrics were hot-pressed to near full density at 1500-1650°C for 1 h under a pressure of 39 MPa in a N 2 atmosphere. However, the composites with 20 and 30 vol% fabrics resulted in delaminated porous ones after hot-pressing due to the exfoliation of filament yarn in woven fabrics. A linear relation of stress-displacement in fracture behavior of monolithic mullite changed to a non-linear relation in the composites with 10-30 vol% of Si-Ti-C-O fabrics and hot-pressed at 1650°C. Addition of Si-Ti-C-O fabrics decreased the four point flexural strength of monolithic mullite (328 MPa) to 292 MPa at 6 vol%, 271 MPa at 10 vol% and 59-78 MPa at 20-30 vol% of fabrics whereas the fracture toughness by the single edge precracked beam (SEPB) method increased from 1.6 MPa m 0 5 for the monolithic mullite to 4 7 MPa m 0 5 for the composites with 10 vol% of Si-Ti-C-O fabrics. Enhancement of the mechanical properties can be interpreted by the partial decomposition of Si-Ti-C-O fibers during hot-pressing at 1500-1650°C, which caused the diffusion of C and Ti elements of fibers to the interfaces between the fibers and mullite matrix. The diffusion of Al from mullite matrix into fibers was also observed. The change of composition, microstructure and strength at the interfaces would increase debonding or pull-out effect of fibers.