The utility model relates to the technical field of industrial mirabilite drying. The drying and dehydrating device is used for producing mirabilite in the chlor-alkali industry. The utility model discloses a drying and dehydrating device for producing mirabilite in chlor-alkali industry. The device comprises a tail gas blower, a spiral feeder, a cyclone dryer, a cyclone separator, a bag-type dustcollector and an alkaline washing tower, a water-containing material sequentially passes through a first section of pulse tube, a second section of pulse tube and a third section of pulse tube through hot air flow of a heat source in an air tube, anhydrous sodium sulphate and mixed air flow are obtained after separation is conducted through a cyclone separator, a large amount of carbon dioxide contained in the mixed air flow is recycled and reacts with alkali liquor, and raw materials needed by production of a downstream procedure are obtained. The device is simple in process and easy and convenient to operate, waste heat in waste gas is fully utilized, carbon dioxide contained in tail gas is fully utilized, the environmental protection pressure in chlor-alkali enterprises is reduced, waste is fully utilized as part of production raw materials, the production cost of the enterprises is reduced, and the device has the advantages of being safe, capable of saving labor, simple, convenient and efficient.