Glycinin and β-conglycinin are the major protein components of soybean, which are different in their structure. The preparation process can cause varying degrees of changes in the structures of glycinin and β-conglycinin. In this paper, a brief overview of the structures of various soybean protein components is given, with a focus on the preparation process of soybean proteins. Moreover, the mechanism for the effect of the structure of soybean protein components on their functions is summarized. This review is expected to provide a reference for the quality control of soybean and soybean protein products.