The invention provides a dietary fiber biscuit premix powder with trehalose additive and a preparation method and an application thereof, and relates to a biscuit premix powder and the preparation method and the application thereof. The aim is to solve the technical problems that the existing biscuits with no sugar additive do not taste crispy enough, the crumps easily fall off during the storage process, the flour must be added and mixed evenly in the end of the biscuit preparation process, the stirring time cannot be too long, otherwise the crispness of the biscuit is affected. The dietary fiber biscuit premix powder with trehalose additive comprises low-gluten wheat flour, sorbitol powder, malt dextrin, wheat fiber, seaweed sugar, xylitol powder, monostearin, sucralose, papain composition and baking soda. The preparation method comprises the steps of firstly weighing material and secondly blending raw ingredients. By the dietary fiber biscuit premix powder with trehalose additive and the preparation method and the application thereof, the papain enzymatic catalysis reactions are utilized, the protein of the dough is degraded into smaller molecule peptides or amino acids, the tensile resistance of the dough is decreased, the dough gets softer and more malleable, the elasticity is reduced, the dough is easy to mold, and the biscuits can be made more crispy.