The invention discloses an apparatus for reducing the content of sulfur dioxide in corn starch. The apparatus comprises a heater; the heater comprises a tank body, an annular heating tube, two stirrers, a separator plate, two temperature sensors, an automatic control regulating valve, two butterfly valves, two discharge valves, two water adding valves and a weigher; and the separator plate divides the tank body into a first independent tank body and a second independent tank body which are connected through a pipeline. A novel oxidant potassium permanganate allowed in the food additive directory is adopted to reduce sulfur dioxide in starch, so adoption of hydrogen peroxide for reducing sulfur dioxide in the corn starch is avoided, and the qualified rate reaches 98% or above; and oxidation of the oxidant on starch particles is reduced, the starch hydrolysis conversion rate is improved by 0.1%, and the content of impurities in a saccharification liquid is reduced by 2%. A problem of unallowed addition of hydrogen peroxide for removing sulfur dioxide in routine food production in the prior art and a problem of starch conversion rate reduction caused by unable hydrolysis or difficult hydrolysis in the production of sugar from gelatinized starch obtained after instant surface gelatinization of parts of starch particles due to high concentration of hydrogen peroxide directly added in the production of non-food starch to remove sulfur dioxide are solved in the invention.