Isoamyl acetate was synthesized by glacial acetic acid and isoamyl alcohol with ionic liquid[(C2H5)3NH][HSO4] as catalyst. The optimal conditions were studied through orthogonal experiment. The effects of reaction time, reaction temperature, the molar of ratio of alcohol to acid and the amount of ionic liquid on the yield of isoamyl acetate were investigated and the optimal conditions were as follows: glacial acetic acid 0.02mol, reaction time 4h, reaction temperature 90℃, the molar ratio of alcohol to acid 0.9:1, the amount of ionic liquid 2g. Under these conditions, the yield of isoamyl acetate was 78.1%, and the ionic liquid could be reused for 4 times without any change of its catalytic efficiency.