Poly(1-oxo-2-phenyltrimethylene) was synthesized by palladium-catalyzed copolymerization of styrene and carbon monoxide in quaternary ammonium ionic liquids. The [Pd(bipy)(2)][PF6](2) compound had relatively more catalytic activity than [Pd(bipy)(2)][BF4](2) in ionic liquids. The catalytic activity of palladium (II) composite catalyst was superior to the catalyst formed in situ from palladium acetate, 2,2-bipyridyl, and X- (X-=PF6-, BF4-) in ionic liquids. The effects of the volume of ionic liquids, reaction time and benzoquinone content on the copolymerization were also described.