Abstract: The theory, process and properties of TiAl based alloy by elemental P/M method have been described in this article. The reaction of elemental Ti, Al at certain temperature is diffusion controlled, including intermediate steps in which TiAl₃ and TiAl₂ phases form. The methods of elemental powder process of TiAl based alloy include:reaction sintering, hot pressing, HIP of elemental Ti,Al powders, hot explosion synthesis, elemental Ti, al foil metallurgy etc. These, methods can fabricate TiAl based alloys with fine, homogeneous microstructure, while their mechanical properties are deteriorated by high content of impurities and flaw.