In order to investigate whether changes in the accounting system of mandatory significantly improve the quality of accounting earnings of listed companies, this paper uses empirical research methods and takes A-shares listed companies in Shanghai and Shenzhen manufacturing industry in the year of 2004-2009 as samples to analyze. The results show that with the constant reform and improvement of Chinese accounting system, the earnings quality of a share shows a significant upward trend on the whole, which demonstrates the changes in the accounting system can promote the earning quality to some extent. At the same time the research discover also shows that simple changes in accounting standards does not improve the quality of accounting information, unless it is accompanied by supporting the strong legal and enforcement mechanisms.