During the last 50 years, the higher education in Korea has rapidly expanded to reach the universal level. Most people has expected that the expansion of higher education would brought a more equal and democratic society. However, many researches still show that there is much difference in educational opportunity between classes. And also, it has been suggested educational and social inequality has been enforced by the stratification structure of universities according to their location, institution type, and the year of founding. I analyzed how the scholastic ability of college students has been changed from 1994 to 2001 to explore the stratification structure of the higher educational institutions. The analysis of the scholastic ability score data showed that the scholastic ability of college freshmen is declining every year in general, and there are clear patterns according to the characteristics of universities such as their location, institution type, the year of founding, and etc. Based on the research findings, I suggested educational and policy implications for decreasing the structured gap between universities and measures for development of higher education at the level of university and government.