The study is based on Youth Project supported by the National Social Science Fund of China named “Research on Public Opinion Construction of National Identity in Social Media”. In order to delineate the behavioral trends of social media users，this article analyzes the differentiation of media preference，use frequency，credibility cognition of information channels and attention to COVID-19 information based on two cross-section questionnaire of 4604 sample data in June 2020 and June 2021. The study illuminates that high-frequency exposure to TV and cell phones declined significantly in the past two years，while heavy exposure to cell phones is still deepening；heavy use of head social media has been alleviated，while the user behavior of mainstream social media become more moderate and short-term. The dominance of domestic central mainstream media in current political news dissemination and media credibility continue to be strengthened，while the influence of overseas media was more subdued. The public is no longer obsessed with repeated exposure to the COVID-19 information at home and abroad，but still maintains a reasonable and stable pace of information updates.