The catalysts silica gel-supported ionic liquid N-methyl-2-pyrrolidinone hydrosulfate( [hnmp]HSO4) were prepared by the sol-gel method and were characterized by using SEM and IR. The catalyst supported ionic liquid was used for the synthesis of aspirin. The effects of preparation conditions of the catalyst,the dosage of supported ionic liquid,reaction temperature,reaction time and the ratio of the reactants on the synthesis of aspirin were investigated. The experimental results showed that the supported ionic liquid possessed good catalytic effect for the synthesis of aspirin,and aspirin yield of 87. 20% was attained under the condition as follows: salicylic acid / acetic anhydride molar ratio 3 ∶ 10,supported ionic liquid1. 0 g,reaction temperature 80 ℃ and reaction time 35 min. The supported ionic liquid still exhibited good catalytic activity after being reused four times.