Titanium aluminide composite reinforced with submicron Al2O3 has been prepared by a reactive hot press method using TiO2, Al and Ti powder as source materials. The reaction synthesis processing is particularly investigated. Results show that the matrix of the as-prepared material is a mixture of TiAl and a small amount of Ti3Al. Fine Al2O3 particles that act as reinforcing phase are dispersed along the interface of the matrix. The reduction of TiO2 involves many transitional stages, including Ti-Al reaction, TiO2-Ti reducing reaction, reaction between TiO2 and Al, etc.