The utility model discloses a system for preventing a catalyst from being clogged. The system comprises a longitudinal flue channel (2) and a horizontal flue channel (3), wherein a dust filtering net A (1) is arranged in the longitudinal flue channel (2); only one end of the filter extinguishing screen (1) is movably connected with the longitudinal flue channel (2); a zipper vibrating and beating device A (4) is connected above the dust filtering net A (1) and is connected with the dust filtering net A (1); an ash bucket A (5) is arranged below the dust filtering net A (1); an ash bucket charge level indicator (20) is arranged in the ash bucket A (5); and the lower end of the ash bucket A (5) is connected with a discharging device A (6). The system can prevent the dust with the particle size of more than 4 cm from entering a catalyst layer, and can automatically discharge dust particles from the dust filtering net without stopping the operation of a boiler, so that the system can perform continuous operation safely and effectively under the condition of lower pressure loss.