The utility model discloses an evaporating plant used in an anhydrous sodium sulfite production process, and relates to an anhydrous sodium sulfite evaporating process and a treatment device for condensed water and secondary steam generated in the evaporating process. The evaporating plant is characterized by structurally comprising a hot water tank and a plate-type condenser; a water inlet of the hot water tank is connected with a shell-pass outlet of a heating chamber of an evaporator, and a water outlet of the hot water tank is connected with a circulating water return header pipe by a hot water pump and a circulating water replenishing tank; and the plate-type condenser is a plate-type heat exchanger, a steam inlet end of the plate-type condenser is connected with a secondary steam outlet of the evaporator, a condensed water outlet end of the plate-type condenser is connected with a water inlet pipe of another hot water tank, and a water outlet pipe of the other hot water tank is connected with a water-side inlet of an alkali proportioning mixing device for a neutralization procedure by another hot water tank. The evaporating plant used in the anhydrous sodium sulfite production process is safe and practical and is simple in operation, problems of recycling, storing and utilizing large quantities of condensed water are effectively solved, application amount of new water is reduced, and environmental pollution due to exhausting of a large amount of alkaliferous condensed water is prevented.