The invention discloses a preparation method of a cassava dregs feed, wherein the method includes the steps: (1) in the presence of a compound enzyme, degrading a mixture of ethanol fermented cassava dregs and cassava starch dregs, to obtain to-be-fermented cassava dregs, wherein the compound enzyme contains cellulase and amylase; (2) in the presence of yeast, carrying out aerobic fermentation of the to-be-fermented cassava dregs, to obtain an aerobic fermented product; and (3) in the presence of lactic acid bacteria, carrying out anaerobic fermentation of a mixture of the aerobic fermented product and a leavening agent. The invention also provides the cassava dregs feed produced by the method. The method can obtain the high-quality feed product, and the ethanol fermented cassava dregs are turned into treasure.