The invention belongs to the field of agricultural product processing, and discloses a method for extracting dietary fiber in banana skin by adopting an enzymic method. The method comprises the operation steps of pretreatment, smashing, enzymolysis, ethonal precipitation, filtrate collection and drying. The extraction of the current dietary fiber generally comprises a chemical method, a fermentation method, a biological enzyme treatment method and the like; because strong acid, strong alkali and high-temperature treatment are adopted for the chemical method, the corrosion to an extracting container, a pipeline and a material pump are quite serious, the acid degree is required to be regulated repeatedly in the extraction process, a great amount of cation and anion are brought in, and the prepared dietary fiber is low in content and poor in color; the dietary fiber prepared by adopting the fermentation method has high content of effective components, is less in pollution, has a long production cycle, is high in cost, and is not beneficial to scale production; and because the catalysis ratio of enzyme is high, the action condition is mild, the enzymic method technology does not require high-temperature high-pressure condition, the equipment requirement is simple, and the effective components have less damage.