The invention discloses a frozen dough modifying agent, which is prepared by evenly mixing an enzyme preparation (including one or a plurality of alpha-amylase, cellulose, hemicellulase, pentosanase, lipase, glucose oxidase, glutamine transaminage and so on), vitamin C, an emulsifying agent, a thickening agent, wheat gluten powder, lecithin and stuffing according to certain proportion. The frozen dough modifying agent has the advantages that the frozen dough modifying agent can effectively improve the stability of dough during fermentation and roasting processes, improve the freezing resistance property of yeasts, increase the volume of finished products, improve the tissue of the finished products, reduce the loss of the vitality of the yeasts during the freezing process, and effectively delay the aging of the finished products.