SiC whisker and Al₂O₃-SiO₂short fiber reinforced AC8A, AC8B and AC8B(J) matrix composites were fabricated by squeeze casting method. Preform deformation, change of reinforcement volume-fraction and formation of macro-segregation in two composites were investigated by using micro Vickers hardness test, analysis of macro and micro structures with OM, SEM and EDAX. Al₂O₃,-SiO₂short fiber preform manufactured with 5% SiO₂binder in this study was considerably deformed and cracked, nevertheless, the short fibers were distributed homogeneously in the composites. In SiC whisker reinforced composites, on the other hand, preform deforming and cracking were not occurred, however, macro segregation zone formed along the infiltration routes by interface reaction during infiltration of molten metal into the preform was observed at center-low area in the composites. The decrease of hardness in the macro segregation zone resulted from the depletion of Si and Mg atoms.