1June, 973, the famous American educational sociologist Martin? At the international conference on the future structure of higher education organized by the World Economic Cooperation Organization (OECD), Trow published the article "Problems in the Transition from Elite Higher Education to Mass Higher Education", and put forward the three-stage theory of higher education development for the first time. Martin? Turow regards the gross enrollment rate of higher education as a quantitative index to measure the expansion of a country's higher education scale and divide its historical development stages, and divides the development process of higher education into three stages: "elite, popularization and popularization". He believes: "Elite higher education in some countries will not change its nature until its scale is expanded to provide learning opportunities for about 15% of school-age youth. When it reaches 15%, the nature of higher education system begins to change and turn to popularization. If this transformation is successful, mass higher education can develop to a certain scale until its capacity reaches 50% of the school-age population, without changing its nature. When it exceeds 50%, higher education begins to move rapidly to the stage of popularization. "