The invention discloses a process method for separating DMF and acetic acid or methanoic acid in sucralose production. The process method comprises the following steps: adding methyl alcohol, a DMF mixed liquid containing acetic acid or methanoic acid, and a solid acid catalyst into a pre-reactor; entering a reaction rectification tower after pre-reaction; filling the reaction rectification tower with the solid acid catalyst; further reacting the acetic acid or methanoic acid which does not react with methyl alcohol in the reaction rectification tower; and feeding a mixture of methyl alcohol, water and methyl acetate or methyl formate at the top of the reaction rectification tower into an existing methyl ester and methyl alcohol separation device in sucralose production, feeding a mixture of DMF and water at the tower bottom into a DMF dehydration tower, and reclaiming at the tower bottom to obtain high-purity DMF. By adopting the method, the problem of separating the highest azeotrope DMF and acetic acid or methanoic acid in actual production can be solved, acetic acid is transformed into useful methyl acetate or methyl formate, the economic benefit is increased, the DMF having a purity more than 99 percent can be reclaimed, and the production cost is greatly reduced.