NOVELTY - Producing feed by biologically modifying food wastes of restaurants and refectories comprises: (i) maintaining the food waste fresh, adding Lactobacillus in the food waste collecting container at the restaurants and refectories; (ii) collecting the fresh food wastes and an assistant material; (iii) inoculating by weighing the assistant material, Bacillus subtilis, brewers yeast, active xylanase and beta glucan and adding cellulose, premixing the assistant material, fermented strain and enzyme and mixing with food wastes; (iv) fermenting; (v) drying, crushing and sieving.    USE - The method is useful for producing feed by biologically modifying food wastes of restaurants and refectories.    ADVANTAGE - The method: produces highly safe feed from the food waste; increases the nutritive value of the food wastes; increases the content of protein and amino acid; improves the water content of material and the venting and radiating functions during fermenting; and has a smooth fermenting process.    DETAILED DESCRIPTION - Producing feed by biologically modifying food wastes of restaurants and refectories comprises: (i) maintaining the food waste fresh, directly adding Lactobacillus in the food waste collecting container at the restaurants and refectories food wastes generating field, feeding once during one collecting period, where the collecting periods is the time period from the beginning till the collecting container becomes full; (ii) collecting the fresh food wastes from restaurants and refectories and an assistant material, where the assistant material is cottonseed meal and/or rapeseed meal; (iii) inoculating by weighing the assistant material (10-40%, preferably 15-35% of dry weight of food waste), weighing Bacillus subtilis and brewers yeast (0.1-2%, preferably, 1-1.5% of the dry weight of food waste), where the mass ratio of Bacillus subtilis to brewers yeast is 6-8:2, preferably 4-6:2, weighing highly active xylanase (100-150 units/g of dry weight of food waste) and highly active beta glucan (150-2000 units/g of dry weight of food waste) and adding cellulose (50-100 units), premixing the assistant material, fermented strain and the enzyme and mixing with the food wastes uniformly and adjusting the water content of the mixture by adding water and/or raw material and/or the assistant material, where the water content is the mixture is 40-60%; (iv) fermenting the mixture obtained in step (iii) at 20-48 degrees C, preferably 30-45 degrees C, where the fermenting period is 40-72 hours, preferably 55-65 hours; (v) drying the fermented material until the water content is less than 15%, crushing the material after drying and sieving until it is less than 20 meshes.