The solidifying structures and fracture appearance of alumina/aluminum silicon alloy composites manufactured by squeeze casting are studied. The results of study indicate that the distribution of alumina fibers is uniform; the fibers can serve as the site for heterogeneous nucleation of silicon phase; and the interface between the fibers and aluminum alloy matrix has great effect on mechanical properties of the composites. Improving manufacturing techniques should be started with controlling interface reaction and fining the structure of the composites.