The invention discloses a production method of a food additive sodium benzoate. The production method comprises the following steps: feeding crude benzoic acid into the bottom of a rectifying tower with side stream withdrawal, controlling the pressure to a range of 1 to 15 kpa, starting heating when the feed level reaches 50-80% of the height of the tower bottom, controlling the tower top temperature to a range of 160 to 175 DEG C, the temperature of the side stream withdrawal to a range of 165 to 180 DEG C and the tower bottom temperature to a range of 190 to 240 DEG C, adjusting the reflux ratio to a range of 0.3 to 1.5, and obtaining refined benzoic acid from a tower top discharge outlet; adding the refined benzoic acid to an aqueous solution containing a sodium compound for neutralization to obtain a sodium benzoate solution, and then decolorizing the sodium benzoate solution with activated carbon and carrying out filtering, drying and dehydrating to obtain the food additive sodiumbenzoate. The production method of the food additive sodium benzoate is simple and convenient to operate with no need for complicated and tedious melting crystallization step, thereby saving a largeamount of energy and a large number of operations for separation and greatly reducing the production cost; and the production method is more conducive to industrial production.