The intermetallic-compounds-strengthened composite was reaction synthesized by hot pressing sintering the mixture of ball-milled Ti-Al powder and TiC+Al2O3 powder. According to the X-ray analysis and thermal analysis (DSC) of the powder and its components analysis of the sintering product, it shows that there are no other compounds but Ti3Al.Through thermodynamic calculation, the author analysized the reaction synthesized process, and found the gradual synthesis process from TiAl3 to TiAl, then to Ti3Al controlled by the diffusion under lower temperature and the formation mechanism of intermetallics compounds at high temperature, and it is in stable state at the interface between matrix and strengthening phases.