A new solid acidic ionic liquid polymer (PIL) has been synthesized through the copolymerization of acidic ionic liquid oligomers and divinylbenzene (DVB). Its oxidation activities were investigated through oxidizing benzothiophene. The results showed that the PIL was very efficient for oxidizing benzothiophene with its oxidation capacity reaching 95.5% at 323 K for 20 min. The oxidation activities were quite high so that the reactions can occur simultaneously under very mild conditions. The PIL exhibits the advantages of high activities and high stability.