The mechanically milled Ti-Al binary composite powders were observed and analyzed using SEM, EPM and TEM. The experimental results show that with increasing milling time, particle sizes of composite powders remarkably and rapidly increase at first, then greatly decrease, and finally decrease to a constant. The Ti particles form "jujube-cake" in Al powders during mechanical alloying. With increasing time, a obvious lamellar structure forms, lamellar spacing decreases and TiIA1 interfaces disappear, and finally amorphous structure forms. However, the Ti-Al intermetallic compounds did not produce during the whole process.