本研究分成兩部分，研究對象為中國大陸之上市公司，第一部分以2004至2009年之財務資料，探討2008年中國大陸企業所得稅法之實施對中國大陸上市公司平均有效稅率之影響；第二部分以1998至2009年之財務資料，探討中國大陸上市公司是否為了因應企業所得稅法實施對有效稅率的影響，而從事租稅誘因盈餘管理之行為。 第一部分之實證結果發現，中國大陸上市公司之平均有效稅率在2008年企業所得稅法實施後有顯著的下降，表示中國大陸上市公司之有效稅率隨著名目稅率降低而下降。外資持股比例超過20%之上市公司（定義為外資企業），其2008年後之有效稅率上升，且內外資企業之其平均有效稅率之差異有縮小之趨勢。屬於高科技產業之上市公司在2008年企業所得稅法實施後，其有效稅率並未下降；但與除了農林牧漁業外之其他產業相比，高科技產業之上市公司其有效稅率較低。第二部分之實證結果發現，在2008年有效稅率下降之上市公司，其於2008年後的裁決性應計項目較大，有將盈餘遞延認列之傾向。 / This study consists of two research issues. The first part uses the financial statement and capital structure data of China listed companies from 2004 to 2009, to investigate the effects of the implementation of the Law of the People’s Republic of China on Enterprise Income Tax in 2008(hereafter 2008 Income Tax Law). And the second part which uses the financial and capital structure data of China listed companies from 1998 to 2009 investigates if China listed companies take the action of earnings management in response to the implementation of the 2008 Income Tax Law. The empirical findings of the first part show that the average ETRs of China listed companies declined after the implementation of the 2008 Income Tax Law. The listed companies whose proportion of foreign ownership is above 20% (defined as foreign enterprises) increased ETRs after 2008 and the differences in ETRs between domestic enterprises and foreign enterprises are reduced gradually. Further, the average ETRs of China listed companies of information technology industry do not appear to be decreased after the implementation of the 2008 Income Tax Law. However, besides the agriculture, forestry, herding, fishery industries, listed companies of information technology industries remain to have lower average ETRs after implementation of the 2008 Income Tax Law. The empirical findings of the second part show that China listed companies whose average ETRs decreased in 2008 appeared to have greater discretionary accruals after 2008, suggesting those companies shifting earnings to 2008.