Several task-specific ionic liquids were prepared by 1-vinylimidazole reacted with bromoacetic acid，3-bromopropionic acid，5-bromovaleric acid and 6-bromohexanoic acid，respectively. Their structures were characterized by 1H NMR and their Bronsted acidities were studied by IR spectra using pyridine as the spectroscopic probe. The results demonstrated that the 1-vinyl-3-acetoxyimidazolium bromide had the strongest acidity among the studied task-specific ionic liquids，the introduction of imidazolium to carboxylic acid can strengthen the acidity of corresponding carboxylic acid because of the electron-withdrawing effects of imidazolium，each task-specific ionic liquid was able to be polymerized with ethylene glycol dimethacrylate to form a white polymer which was characterized by scanning electron microscope.