The Knoevenagel condensation reaction has been widely used to prepare fragrance, chemical materials and pharmaceuticals. With ionic liquids as reaction solvents, reactions of a wide range of aldehydes and ketones with methylene compounds proceed smoothly. Functional ionic liquids as catalysts can successfully catalyze Knoevenagel reactions in the absence of any other catalyst. Ionic liquids, as “green” and “designer” solvents, provide a high efficient and environmental friendly approach for Knoevenagel reactions. In this paper, the progress in the use of ionic liquids for Knoevenagel condensation reaction is reviewed.