Abstract: The microstructure and the chemical compositions in micro-zone of densified TiAl base alloy specimen manufactured from 1:1 Ti-Al mixture by reaction hot-pressing have been reviewed and analysed by using scanning electronic microscope.According to the distribution of Al element and composition range in various phases,it has been found that during the process of reaction between Ti and Al,four phases TiAl 3,TiAl,Ti₃Al and α-Ti were firstly formed in original Ti particles. Then continuous reaction among these four solid phases was carried out.With the diffusion and homogenization of Al element,the TiAl₃ and α-Ti phases which have been formed were eliminated.Finally,the microstructure was constituted by two phases TiAl and Ti₃Al.