Abstract: 6-ethoxycarbonyl-3-phenyl-5-(4-chloro)phenyl-2-cyclohexenone could be synthesized through one-pot Robinson annelation from ethyl acetoacetate with 3-(4-chloropheny)-1-phenyl-2-en-1-one in good yield catalyzed by task-specific ionic liquid, 1-ethyl-3-methyl imidazole hydroxyl (emim OH). This process wass simple, high yield, environmentally benign and the catalyst could be recycled. The possible reaction scheme was studied.