The processing and mechanical properties of 3-dimensional brainded carbon fiber preform reinforced alumina (Al₂O₃) matrix composites prepared by sol-gel method were investigated. The influences of different sols prepared from Al(NO₃)₃ and AlCl₃ hydrolysis, respectively, on the processing and mechanical properties of composites were also studied. Composites I# and II# were prepared from the sols with Al(NO₃)₃ and AlCl₃ as starting material, respectively. The viscosity of the sol Prepared from Al(NO₃)₃ hydrolysis was lower than that from AlCl₃ hydrolysis, so the densification rate of composite I# was faster than that of composite II#. After 13 times of sol infiltration-gelation-pyrolysis, the density and the flexural strength of as-fabricated composite I# reached 1.86g/cm³ and 145.2MPa, respectively, while those of composite II# reached 1.63g/cm³ and 104.1MPa, respectively. SEM observation of all the specimen fracture surfaces showed a large amount of fiber pull-out. It illustrated that the carbon fiber played a role of toughening Al₂O₃.