TiAl-based alloys (TiAl-based intermetallics) are considered as an ideal novel light-weight high temperature structural material, which have a broad application prospect in civilian, weapon and aerospace industries. However, due to the brittleness of TiAl-based alloys, it is difficult to produce complex structural components by traditional forming methods, seriously restricting the popularization and the application of TiAl-based alloys. According to the layered slice data of the CAD model, selective melting 3D printing uses laser or electron beam as high energy heat source to scan and melt the powder layer by layer, and the manufacturing of parts is directly realized by the layer by layer stacking method. Selective melting 3D printing represents the most advanced and novel technology of TiAl-based alloys forming. In this paper, based on the latest research results of TiAl-based alloys prepared by selective laser melting (SLM) and selective electron beam melting (SEBM), the formation causes and control measures of common defects in the forming process are summarized emphatically, and the influence laws of process parameters on forming quality, microstructure and mechanical properties are elaborated in detail. Furthermore, the advantages and disadvantages of SLM and SEBM to produce TiAl-based alloys are compared and analyzed. The Chinese and international research results show that controlling the cracking tendency of TiAl alloys is the most important problem to be solved for TiAl alloys prepared by SLM, and is also the basis for improving the density and mechanical properties of the formed parts. By optimizing the process, SEBM can better restrain the cracking of TiAl alloys and obtain high density formed parts, of which the mechanical properties can reach the level of traditional forgings and castings. Therefore, SEBM is more suitable for 3D printing of TiAl alloys. Suggestions for further development on selective melting 3D printing of TiAl-based alloys are proposed finally.