The implementation of accreditation system for higher education in the United States has lasted more than 100 years and it is the most diverse and mature assessment system in the world. It is mainly based on folk power,which aims at the certification of recognized institutions,so as to guarantee and enhance the quality of education,teaching and scientific research. This paper tries to comb the historical reasons of American higher education accreditation system and compare the connotation of the new version 2. 0 with that of its predecessor version,and analyze the problems existing in this new system and its future trend,in order to reform and further improve the assessment system of higher education in China.