The invention provides a biological active environment-friendly aquatic feed preparation method which comprises the steps of preparing fermented wet-based bean pulp and adding the fermented wet-basedbean pulp into complete feed. The preparation method specifically comprises the following steps: S1), activating culture; S2), preparing an enzyme solution; S3), mixing and inoculating; S4), stackingand fermenting; S5), mixing the fermented wet-based bean pulp with raw material rapeseed meal in a formula of the complete feed according to a certain mass proportion; S6), smashing the mixed raw materials in the S5), putting into a mixing material cabin to be mixed with the rest of complete feed, regulating and granulating. The preparation method disclosed by the invention has simpleness in preparation and effectively solves the problems of high dose and high-efficiency adding of the fermented wet-based bean pulp; furthermore, a small peptide content of the fermented wet-based bean pulp is high, so that viscosity is improved; in addition, water resistance of the complete feed is improved, pollution of residual feed to water environment is reduced, the water quality environment degradationis effectively solved, diseases of aquatic livestock are reduced, and high quality and high yield of the aquatic livestock are ensured; furthermore, water resistance of the complete feed is improvedby 40 to 60%, and effects of the residual feed to the water quality are remarkably reduced.