The invention relates to the technology field of combustion equipment, and discloses a stack gas desulfurization tower of a circulating fluid bed, which is used for smoke gas purification. The stack gas desulfurization tower comprises a purified smoke gas outlet, an atomizing water jet apparatus, recycling ash nozzles, a desulfurizer inlet, and a smoke gas inlet which are arranged on a tower body. The stack gas desulfurization tower is characterized in that functional air nozzles are arranged on the tower body and positioned under recycling ash nozzles; at least a wind-pressure desulfurizer jet apparatus is arranged on the tower body and positioned under the functional air nozzles; a plurality of Venturi nozzles are arranged inside a Venturi throat in the tower body; the wind-pressure desulfurizer jet apparatus has the structure that an air inlet pipe is provided, the desulfurizer inlet is arranged on the air inlet pipe, and a diffuser nozzle is arranged on the head end of the air inlet pipe, wherein, the head end of the air inlet pipe extends into the tower body; the recycling ash nozzles and the functional air nozzles are both a plurality of nozzles. The stack gas desulfurization tower has the advantages of reasonable structure, low investment, low running cost, reliable running, high efficiency, wide application range, etc.