Superplastic pseduo deformation for 20 vol.% SiC whisker reinforced 2024Al matrix composites has been investigated. The composites were fabricated by vacuum hot pressing process, and hot extruded at ratios of 10:1, 15:1 and 25:1. Tensile tests were conducted at 475℃, 500℃, 525℃ and 550℃ at strain rates rainging from $10^{-3}$ to 1.7 $S^{-1}$. Microstructures of each sample have been characterized by transmission electron microscopy and scanning electron microscopy. As-pressed composites exhibited elongations about 10 pct, but the extruded(25:1) composites exhibited the maximum elongation of 150 pct for a maximum strain rate sensitivity 0.5 at 550℃ and strain rate of about $10^0s^{-1}$. The maximum elongation obtained at the high strain rate of about $10^0s^{-1}$, and the optimum elongation increased with increasing temperature and increasing extrusion ratio. Strain rate sensitivity values(m) were 0.1-0.2 for the strain rate range $10^{-3}10^{-1}s^{-1}$, but for high strain rate range $10^{-1}-10^0s^{-1}$, m values were 0.3-0.5. High extrusion ratio could produce fine grain size, and more uniform SiC whisker distribution, resulting more elongation. The flow curves with increasing temperature are similar, and there is no evidences operating different mechanism of superplastic deformation through temperature range 475℃ - 550℃. Superplastic deformation of $SiC_w$/2024Al could be described as combination of matrix grain boundary sliding and whisker matrix interface sliding.
