6-Hydroxy-3,4-dihydro-2(1H)-quinolinone was synthesized by one-pot reaction of 4-methoxyaniline and acryloyl chloride using [bmim]Cl-AlCl3 ionic liquid as catalyst, and its structure was characterized and confirmed by IR, elemental analysis and 1H NMR spectra. Firstly, N-(4-Methoxyphenyl)acrylamide was obtained by acylation of 4-methoxyaniline using acryloyl chloride in [bmim]Cl-AlCl3. Secondly, with the cooperate catalysts of [bmim]Cl-AlCl3 and HCl produced by acylation, 6-hydroxy-3,4-dihydro-2(1H)-quinolinone was produced with a yield of 89.6% through intramolecular Friedel-Crafts alkylation and demethylation of N-(4-methoxyphenyl)acrylamide. As a task-specific ionic liquid, [bmim]Cl-AlCl3 plays the role as catalyst as well as solvent. And it can be recycled and utilized for five more times without significant decrease in the yield of the target compound.