A series of task-specific ionic liquids (TSILs) with imidazolium and pyridinium that bear an alkane sulfonic acid group were synthesized. The synthesis of benzyl octanoate used benzil alcohol and octanoic acid as reactants and these TSILs as catalyst was investigated. Effect of anion and cation of TSILs on their catalytic performance was also investigated. The results showed that the conversion of octanoic acid reached 95.3% by using [PSPy]HSO4 as catalyst under conditions of n octanoic acid : n benzil alcohol= 1:1.5, 20 mol% of octanoic acid for TSILs, 120℃ and 2.5 h. In addition, the [PSPy]HSO4 exhibited excellent stability and catalytic activity. It could be reused ten times without considerable loss of activity and still had a conversion of 94.2%.