Abstract: Based on ranking made by Chinese Academy of Sciences(CAS) Library, the paper makes an analysis and study of SCI journals published in 2014-2018 and their ranking. By analyzing the causes of the change in ranking, the paper aims to explore the influence of such change on the quality of journals and the evaluation of scientific research achievements. The analysis shows that new journals, the change of journal discipline category, the change of impact factor, and the adjustment of journal ranking rules are the main reasons for the change of journal ranking. The journal ranking reflects the quality of journals and affects the evaluation of scientific research performance of scholars and institutions. Hence it is necessary to set up a relatively complete quality evaluation system of journals in combination with various evaluation criteria.

Key words: Chinese Academy of Sciences, Journal ranking, Ranking change, Influencing factors