The invention discloses bio-fermented feed capable of improving reproductive performance of sows as well as a preparation method and an application of the bio-fermented feed, and belongs to the technical field of feed for the sows. The fermented feed comprises the following raw materials: corn, extruded soybean, Fortide, dietary fiber, fish meal, dehulled soybean meal, emulsified flaxseed oil, glucose, wheat bran, flour, calcium hydrogen phosphate, calcium formate, edible salt, choline chloride, lysine, methionine, threonine, probiotics, a Chinese herbal medicine additive, an acidulant, micromineral elements and vitamins. The bio-fermented feed aims to improve reproductive performance of the sows and reduce diseases in a reproductive process of the sows, provides the sows and fetuses withnutrition supply in the reproductive process, increases parturition rate of the sows and survival rate of the piglets and can shorten post-reproduction recovery time of the sows and excavate reproductive potential of the sows.