The aim of this study was to determine the effects of different extrusion conditions on the saccharification characteristics(initial reaction velocity, reaction rate constant, yield) of extruded corn starch. Extruded corn starch-water slurries were mixed with alpha-amylase for the enzymatic saccharification. The saccharification yield of extruded corn starch was high at lower feed moisture content and higher barrel temperature. The solubility of extrudates increased with increase in the SME input which increased with increase in the feed moisture content. Starch hydrolysates having DE 63.8 was obtained after 2 hrs reaction. The initial reaction velocity of the extrudate slurry with alpha-amylase was higher with decrease in the feed moisture content. The initial reaction velocity of extruded corn starch was the highest (2.26×10^-3mmol/mLㆍmin) at 25% feed moisture content and 120℃ barrel temperature, 250 rpm screw speed. The pregelatinized starch was 1.83×10^-3mmol/mLㆍmin as a control. Reaction rate constant is similar trend as initial reaction velocity.