The polymer P(MMA-DMC) was synthesized from methyl methacrylate (MMA) and methyl acryloxyethyl trimethyl ammonium chloride (DMC) as raw materials. By the adsorption of P(MMA-DMC) on Rose red (RB), UCST(High critical dissolution temperature) type RB catalyst P(MMA-DMC)-RB was prepared. The UCST temperature and the stability of P(MMA-DMC)-RB dissolved in solution were determined. The catalytic activity and stability of P(MMA-DMC)-RB catalyzed the reaction of N-phenyltetrahydroisoquinoline derivatives with nitromethane were studied. The results show that when DMC content is 0.5%~2% (DMC content is calculated based on MMA content),UCST temperature is 35~42℃,After four dissolution-precipitation experiments of P(MMA-1%DMC)-RB, the recovery can still reach more than 93% of the first time. In the CDC(cross dehydrogenation coupling reaction) between N-phenyltetrahydroisoquinoline derivatives and nitromethane,P(MMA-1%DMC) -RB has a high catalytic activity, and its catalytic performance is comparable to that of conventional rose Red RB. The yield of N-phenyltetrahydroisoquinoline was more than 80% when the reaction temperature was 45 and the white 1W LED light source was used for 8h. Moreover, the UCST RB catalyst has good adaptability and stability. After 8 times of application, the yield of N-phenyltetrahydroisoquinoline compounds decreases from 90.2% to 77.9%.