This paper reports the fabrication of SiC toughened by in situ synthesized TiB 2 based on pressure-less sintering technique using TiO 2 , B 4 C, C and SiC as starting materials. The process conditions were investigated in detail, including the pre-sintering temperatures, carbon contents, differently sized TiO 2 powders, TiB 2 volume contents, final sintering temperature and time. These conditions were found to have great influence on the TiB 2 toughened SiC in terms of relative density, TiB 2 particle size and fracture toughness. Homogeneous dispersion of in situ synthesized TiB 2 secondary phase was confirmed to enhance the K IC of the SiC matrix. The K IC of SiC toughened by in situ synthesized TiB 2 (15vol%) reaches 6.3MPam 1/2 , which is among the highest values reported so far on TiB 2 reinforced SiC composites based on the pressure-less sintering technique using TiO 2 as Ti source.