Br(o)nsted acidic ionic liquids based on imidazolium cation were employed as a series of environmentally benign catalysts and mediums in the alcoholysis of acetonitrile to synthesize ester. The results showed that Br(o)nsted acidic ionic liquid [HSO3-pmim]HSO4 was an efficient catalyst and medium for the alcoholysis of acetonitrile which could be recycled easily without obvious decline in catalytic activity, the highest yield could reach 85%.