The invention discloses ionic liquid capable of absorbing sulfur dioxide as well as a preparation method and application of the ionic liquid. Cations of the ionic liquid are nitrogen-containing organic matters and anions of the ionic liquid are organic acid groups. The nitrogen-containing organic matters are selected from one or ore of guanidine salts, alcamines, imidazoles, pyridines, tetrazoles, quaternary ammonium salts, thiazoles ad dicyandiamides matters; and the organic acid groups are selected from one or more of lactic acid, tartaric acid, citric acid, methanesulfonic acid, trifluoroacetic acid, malic acid, oxalic acid and acetic acid. The ionic liquid disclosed by the invention has a relatively good absorption effect on SO2 and relatively high selectivity. The preparation method is simple, reaction conditions are moderate, the raw materials are cheap and easily available, and the product has stable performances. An absorbent prepared from the ionic liquid has high absorption efficiency, can be cyclically utilized and has good stability, and can be used for absorbing the SO2 in flue gas at a high temperature; and the inactivation of the absorbent, caused by the fact that the ionic liquid is decomposed, is avoided.