In order to investigate the influence of the implementation of the new Enterprise Income Tax Law from microscopic level, this paper takes annual tax discrepancy of listed companies in China as samples to analyze the change of the actual tax burden. It draws the major conclusions as follows: (1) the law has brought the actual average tax burden of listed companies down in 2008, but the fall among different groups is not the same, the effective tax rate (ETR) of the firms with nominal tax rate reduction during the tax reform has declined by a big margin, and other firms’ ETR has been unchanged; (2) policy effect of the tax reform was completely released in 2008, the ETR of listed companies hasn’t gone further down in 2009; (3) In 2009, ETR of the firms whose nominal tax rate increased by 10% during the tax reform in 2008 is significantly higher than that of 2007. All conclusions above suggest that tax preference brought by the new law is effective, and the New Enterprise Income Tax Law brings smooth transition of the firms’ ETR.