Abstract: Al₂O₃, Al₃Ti/Al in situ aluminum matrix composite material was prepared by means of XD(exothermic dispersion)synthesis technique. Its kinetic mechanism was also discussed. The results showed that the Al-TiO₂system can react in a very short time. The reaction was propagated in combustion wave. It was also shown that aluminum initially reacted with TiO₂ to form Al₂O₃ and reduced Ti. The Al₂O₃ and Al₃Ti took the shape of equal axial particle and block respectively. A certain heating rate and content of aluminum are needed, if thermal explosion occurs commonly in the Al-TiO₂ system. The bulk shrinkage will be higher with lower heating rate, higher aluminum content and lower green density.