The invention relates to a method for producing biological feed by fermenting byproducts from deep processing of corns, which belongs to the field of fermentation engineering. The method comprises the steps of respectively culturing strains of bacillus subtilis, lactobacillus and microzyme, mixing the bacillus subtilis strain, the lactobacillus strain and the microzyme strain according to the ratio of 1:1:3 to obtain fermenting strain liquid, mixing corn bran, corn pulp, sugar slag and corn germ dregs according to a given ratio to obtain a fermenting culture medium, adding the fermenting strain liquid into the fermenting culture medium, uniformly mixing the fermenting strain liquid with the fermenting culture medium to obtain a mixture, filling the mixture into a vacuum bag, sealing, compacting, culturing and fermenting the mixture at the temperature of 37 DEG C for 60h, and taking out the mixture. By adopting the method, the disease-resistant immunity of animals can be improved, the micro-ecological balance of animal intestines can be improved, and the animal product quality can be improved; in addition, the animal immunity can be enhanced after different living probiotics produced in the fermentation process enter the animal body, the utilization rate of the feed raw material can be increased, and the breeding cost can be reduced.