This paper briefly reviews the research history of TiAl intermetallic compounds. Based on reviewing the research of TiAl single crystals, we focus on the breakthrough in theory, preparation technology and mechanical properties of the new generation of high-performance high-temperature polysynthetically twinned (PST) TiAl single crystals. We further analyze main research of PST TiAl that needs to be carried out in the future. Finally, we prospect the application of this novel PST TiAl single crystals in aero-engine blades.