The present invention relates to the field of biotechnology and particularly relates to a method for preparing a soybean Aglycin family peptide by using acetic acid. The method for preparing the soybean Aglycin family peptide by using acetic acid comprises the following steps: subjecting raw materials to cleaning, soaking, germination, grinding and extraction, separating the slag from the slurry through a ceramic membrane and an organic membrane, and subjecting obtained materials to freeze-drying. According to the technical scheme of the invention, the acetic acid is extracted from soybeans, and the ceramic membrane and the organic membrane are combined to use, wherein the pore size of the ceramic membrane is 0.1 [mu]m and the pore size of the organic membrane is 1500 D to 6000 D. In this way, small protein and polypeptide compounds, with the molecular weight thereof between 1500 D to 6000 D, are obtained. The method is simple in operation, thoroughly in extraction effect, easy in filtration, short in production cycle, greatly improved in yield and greatly reduced in production cost. Therefore, the industrial production is easily realized. A produced Aglycin product is in the form of light yellow powders, and is good in taste and high in purity. The Aglycin product can be used as functional food for the adjuvant therapy of type 2 diabetes for preventing diabetes.