The Ti-Al system intermetallic compounds and composites fabricated through Ti and Al，such as TiAl3, γ-TiAl and α-Ti3Al intermetallic compounds, and Ti/Al, Ti/Ti3Al, Ti/TiAl, Ti/TiAl3 and Al/TiAl3 metal-metal and metal-intermetallic compound composites, have good application prospects in aerospace, automotive and other fields owing to their excellent physical, chemical and mechanical properties. The preparation of the above materials involves a variety of Ti-Al reaction diffusion processes. Therefore, an in-depth understanding of the Ti-Al reaction diffusion mechanism and kinetics will help to prepare Ti-Al intermetallic compounds and composites reasonably and efficiently. At present, the Ti-Al reaction diffusion mechanism and kinetics has been extensively studied, but there are still many divergences on some conclusions. In this paper, the research progress of the reaction diffusion mechanism and kinetics involved in the preparation of Ti-Al intermetallic compounds and composites is reviewed, and the future research direction of Ti-Al reaction diffusion is prospected.