The present invention relates to a method for separation and recycling of pure sulfur dioxide from a gaseous mixture in the IS cycle. More specifically, the present invention relates to a method for separation and recycling of pure sulfur dioxide from a gaseous mixture in the IS cycle using an ionic liquid under a specific condition. When compared with the conventional amine-based absorbent, the use of the ionic liquid enables continuous absorption and stripping of SO.sub.2 even at high temperature, and enables a reversible absorption of SO.sub.2 without loss, decomposition or degradation of a solvent due to good chemical stability, thereby enabling separation and recycling of pure SO.sub.2 from a gaseous mixture in the IS cycle.