A device for preparing a sulfite includes: a mother liquid tank and alkaline bin connected to a concentrated alkaline tank, connected to a tower reactor first reactor, one first reactor bottom output end is connected to a first gas-and-liquid mixer and another to a bubbling reaction kettle upper end, a bubbling reaction kettle gas output end is connected to the first mixer being connected to a first reactor upper portion; first reactor upper portion gas and second reactor bottom output ends are connected to a second mixer being connected to the second reactor top; and the bubbling reaction kettle is connected to a centrifugal machine or the alkaline tank, the machine being connected to a wet material bin and the liquid tank. A method includes preparing main and auxiliary absorption liquids, generating a middle slurry, reabsorbing residual gas SO.sub.2, generating a target product, separating the target product, drying and packaging.

A device for preparing a sulfite includes: a mother liquid tank and alkaline bin connected to a concentrated alkaline tank, connected to a tower reactor first reactor, one first reactor bottom output end is connected to a first gas-and-liquid mixer and another to a bubbling reaction kettle upper end, a bubbling reaction kettle gas output end is connected to the first mixer being connected to a first reactor upper portion; first reactor upper portion gas and second reactor bottom output ends are connected to a second mixer being connected to the second reactor top; and the bubbling reaction kettle is connected to a centrifugal machine or the alkaline tank, the machine being connected to a wet material bin and the liquid tank. A method includes preparing main and auxiliary absorption liquids, generating a middle slurry, reabsorbing residual gas SO.sub.2, generating a target product, separating the target product, drying and packaging.