The invention discloses an automatic feedback supplementing method for high-density culture of lactic acid bacteria, and belongs to the field of microbial fermentation engineering. According to the automatic feedback supplementing method disclosed by the invention, in the culturing process of the lactic acid bacteria, alkali liquor is automatically added according to a pH value so as to keep a neutral environment of a culture system; a supplementing pump is associated with an alkali supplementing pump, so that a supplementing culture medium and the alkali liquor are automatically added into the culture system according to a certain ratio, thereby ensuring stability of concentration of a substrate in the culture system. According to the automatic feedback supplementing method disclosed by the invention, not only is the requirement of bacteria for the substrate ensured, but also the substrate is automatically added according to consumption of the bacteria without exceeding the standard. The method disclosed by the invention is applicable to all homofermentative lactobacillus fermentium, such as lactobacillus casei, lactobacillus plantarum, lactobacillus rhamnosus, lactobacillus acidophilus, lactobacillus helveticus, lactobacillus bulgaricus and the like, and all bifidobacterium, such as bifidobacterium bifidum, bifidobacterium adolescentis, bifidobacterium animalis, bifidobacterium longum, bifidobacterium breve and the like.