The utility model relates to a water-curtain high-efficient desulfurization and dust removing device used in an internal cylinder of a chimney of a coal-fired boiler and comprises a water intake pipe, a water return pipe and nozzles, wherein, an internal cylinder which is arranged in a chimney of a boiler is provided and the cylindrical wall of the internal cylinder clings to the internal wall of the chimney; the nozzles are arranged in the internal wall of the internal cylinder and connected with the water intake pipe; a spray port of the nozzles is an approximate circle and the water sprayed out inclines downward from 5 degrees to 15 degrees and covers the water-curtain plane of the periphery of more than 300 degrees; the nozzles in the four sides of the internal cylinder are arranged on the upper and the lower with intervals and each side is provided with one nozzle to four nozzles; the internal cylinder is provided with a smoke inlet which coincides with a smoke inlet of the boiler; the water return pipe is communicated with a sedimentation pool of a return water treatment pool communicated with the water inlet pipe. The utility model is suitable for the dust removing for the chimney of a cola-fired boiler and has the advantages of novel structure, low running cost, flexible use, strong adaptability and good dust removing effect.