Three-component Mannich reaction of cyclohexanone, aromatic aldehydes and aromatic amines catalyzed by a basic functionalized ionic liquid，1-butyl-3-methylimidazolium hydroxide (［bmim］OH), was investigated. Under the optimum reaction conditions as n(cyclohexanone)：n(aromatic aldehydes)：n(aromatic amines)：n(［bmim］OH)=1：1：1：0.1, and at room temperature for 10 h with CH₃CH₂OH as a solvent, the yields of β-amino ketones was obtained with 75%-91%. The factors influencing the Mannich reaction were discussed including solvents, the structure of aldehydes and amines. The ionic liquid, which is environment friendly, was recycled at least 5 times without significant loss of activity.