To investigate microstructural influence on deformation behavior, TiAl-based alloys were prepared by spark plasma sintering and heat treatment was conducted to optimize the microstructures of as-sintered samples. The near-γ microstructure of the sintered alloy transformed into a duplex microstructure after heat treatment. Furthermore, isothermal compression tests were carried out at different temperatures in the range 1100–1200°C with a strain rate of 0.01 s−1. The resistances to deformation of the heat-treated samples were smaller than those of the as-sintered samples under the same deformation conditions. In particular, the heat-treated sample had fewer and smaller α2 phases than did the sintered alloy, and it exhibited a well-deformed appearance and homogeneous microstructure after deformation at a temperature 100°C lower than the sintered alloy. The results revealed that TiAl-based alloys with an optimal microstructure fabricated by powder metallurgy had good formability and a homogeneous deformed microstructure, which was preferable for hot-working and further secondary processing.