The invention belongs to the technical field of lactic acid fermentation, and particularly relates to a method for production of lactic acid and joint production of protein feed by cyclic fermentation. The method is characterized in that the existing lactic acid production technology of simultaneous saccharification and fermentation is used as the basis, the pretreatment method of lactic acid fermentation bacteria residues is combined, and the bacteria can be cyclically utilized; by utilizing single batch of bacteria, the multi-cycle fermentation can be realized, the disposal problem of fermentation waste residues is solved, and the consumption of raw and auxiliary materials is decreased; the composite medium can be cyclically used, so that the resources can be recycled. The method for production of lactic acid and joint production of protein feed by cyclic fermentation has the advantages that by using an automatic plate frame filter technique, the corn starch residues in the saccharification process are quickly separated; the separated corn starch residues are solidly fermented to jointly produce the protein feed, the content of amino acids is obviously increased, the components of starch residues can be conveniently digested and absorbed by animals, and the corn protein feed with high addition value is prepared.