The invention discloses an ultralow boiler smoke emission device. The ultralow boiler smoke emission device comprises a coal fired boiler, a denitration reactor, a bag type dust remover and a desulfuration tower. The coal fired boiler comprises a hearth, a main combustor and a flue. The main combustor is arranged at the lower portion of the hearth. Two layers of over fire air spraying ports are formed in the upper portion of the hearth. A smoke guide-out pipeline and a smoke guide-in pipeline are arranged between a previous-level economizer and a previous-level air pre-heater in the flue and are connected with an inlet and an outlet of the denitration reactor correspondingly, and an outlet of the flue is sequentially connected with the bag type dust remover and the desulfuration tower. The desulfuration tower is internally provided with a washing section, an absorption section and a mist removing section from bottom to top. Two water washing spraying layers are arranged above the absorption section, and a PP filler layer is arranged between the upper water washing spraying layer and the lower water washing spraying layer. The mist removing section is sequentially provided with a pipe type mist remover and a ridge mist remover from bottom to top. By means of the ultralow boiler smoke emission device, the content of NOX, SO2 and soot in the boiler smoke can be reduced, the national ultralow emission standard is met, and long-period running target of the device is achieved.