By using thermal simulation technique, the conventional canned-forging process of TiAl based alloy was studied. The effect of can parameters on the microstruct ures of TiAl alloy was analyzed in this process. The results show that, the defo rmation microstructure of TiAl based alloy without canning is inhomogeneous. In lateral area, crack and shearing lines can be found; while in central area, fine -grained shearing zone can be found. The effect of can is to reduce the seconda ry tensile stress. However, only when the deformation of the steel can is coinci dental with that of TiAl alloy ingot, can this effect be effective. Moreover, a thick can would enhance the microstructural homogeneity in TiAl based alloy. With the H/D ratio of the ingot increasing, the deformation of TiAl alloy would be more unsteady, therefore, a thicker can should be needed.