A TiC whisker toughening Al2O3 composite ceramic tool material was developed by an in situ carbothermal reduction synthesis technology. The influence of different synthesis temperatures (1480°C and 1700°C) and holding times (90min, 60min and 30min) on the mechanical properties of the composite was investigated. The results showed that either the lower synthesis temperature (1480°C) or the higher synthesis temperature (1700°C) was necessary to the improvement on the fracture toughness of the composite. However, when an Al2O3-TiO2 eutectic system was formed during the higher temperature synthesis process, grain coarsening of the Al2O3 matrix became much serious, which resulted in obvious decrease in the flexure strength of the composite. Therefore, the carbothermal reduction synthesis process should be divided into two parts including the lower temperature synthesis process for increasing the yield of the TiC whisker and the subsequent higher temperature synthesis process for increasing the carbon content in the TiC whisker, and and the lower temperature synthesis process should be held for enough time (e.g. 60min) to avoid an incomplete carbothermal reduction of TiO2.