The invention provides a high-density fermentation culture medium for feed lactobacillus brevis and a fermentation method thereof, and belongs to the field of fermentation of probiotics. The high-density fermentation culture medium has the advantages that for the lactobacillus brevis ZLB004, under the conditions of optimum high-density fermentation culture medium and fermentation, a constant-pH (potential of hydrogen) glucose supplementing and adding control strategy is adopted, and the number of living bacteria in fermentation liquid is more than 1010CFU/mL, and is increased by more than 20 times in comparison with the number of living bacteria cultured by the common MRS (Man, Rogosa and Sharpe) culture medium and conventional method; the high-density fermentation of lactobacillus brevis is realized, the culture volume is reduced, the production cost is reduced, and the production efficiency is improved.