The invention relates to a method for carrying out biological modification upon erythromycin bacteria residue and for reusing the modified product in fermentations of antibiotics such as erythromycin or macrolide. According to the erythromycin bacteria residue biological modification method, erythromycin bacteria residue and other industrial and agricultural by-products are adopted as substrates; a selective mixed flora is inoculated; compound enzyme preparation solid-state fermentation is carried out; and steps such as drying, crushing, sieving, packaging and the like are carried out. The treatment method provided by the invention has the characteristics of simple production process, easy operation, short treatment time, and high treatment efficiency. Compared with the original bacteria slag (with protein content of 17-25% and ash content of 21-27%), the protein content of the modified product (with protein content no lower than 28% and ash content no higher than 15%) is increased by 12-65%, and an ash content is reduced by 29-44%. The product can be reused as a fermentation medium for antibiotics such as erythromycin or macrolide, and fermentation titer can be improved. The invention provides a novel approach for solving problems of environment pollution and waste recycling in erythromycin production.