The invention relates to the field of microbial fermentation feeds, particularly discloses an extruded expansion type biological fermentation feed and a preparation and use method thereof, and aims atsolving the technical problems that the nutrition of an existing biological feed is easy to lose and not easy to preserve. The extruded expansion type biological fermentation feed is prepared from basic extruded expansion pellet feed and a compound fermentation solution, wherein the basic extruded expansion pellet feed comprises fish meal, shrimp meal, soybean meal, rapeseed meal, cotton seed meal, corn, flour, cassava pieces, bran, soybean oil, a vitamin premix, a trace element premix, monocalcium phosphate, vitamin C and choline chloride; the compound fermentation solution comprises a compound strain, a complex enzyme preparation, cane molasses or glucose and water. The preparation method comprises the steps that 10-30% of the compound fermentation solution is inoculated into the basicextruded expansion pellet feed, fermentation is carried out, and the extruded expansion type biological fermentation feed can be obtained. The biological fermentation feed meets the nutritional requirements of aquaculture animals, and can be effectively utilized, and beneficial bacteria and nutrients are not easy to lose but easy to preserve.