La-modified TiAl3 intermetallics were prepared by combined processing of mechanical alloying and annealing. The effects of adding lanthanum on the microstructure and mechanical properties of TiAl3 were investigated by XRD, particle size and distribution analysis, TEM, the tests of hardness, elongation and fracture toughness. The results show that adding trace element lanthanum can make the DO22 type TiAl3 crystal structure transform into the related cubic L12 structure. The fracture toughness of alloys modified by adding La can be increased by 143.75%. However, the Vickers hardness of the Al-Ti-La powders is smaller than that of the Al-Ti powders