本研究主要目的在探討大陸於2008 年實施的新制企業所得稅法－《中華人民共和國企業所得稅法》，對大陸產業與內外資企業的影響。大陸新制企業所得稅法改變舊制兩法分立的課稅方式，將內、外資企業所得稅法加以統一。本研究透過實證資料，分別以新稅法施行前後各三個年度，就不同產業以及是否為外資企業等層面，分析大陸上市企業在新稅法施行前後，平均有效稅率的差異變化。研究結果發現，整體上市企業在新稅法實施後，其平均有效稅率呈顯著下降；而各產業因優惠方式不同而呈現上升與下降不一的情況；至於內資企業的平均稅負則呈顯著下降，而外資企業則顯著上升；但外資企業的平均稅負仍舊低於內資企業。另一方面，複迴歸分析結果亦顯示，企業在新稅法實施後，其平均有效稅率顯著較兩稅合一前為低；同時有效稅率與企業規模、期末存貨呈顯著正向關係，而與長期投資額、資本密集度、發行H股、國有股持股比例、外資持股比例以及資產報酬成長率呈顯著反向關係。

The main purpose of this research is to compare the tax burden of listed
companies in China before and after the adoption of the “Enterprise Income
Tax Law” in 2008. Through empirical data, we find that after the implementation of the new enterprises income tax law, the average effective
tax rate（ETR）significantly decreased. However, if we separate all sample
into two groups, the average ETR increased for foreign enterprises group and decreased for the group of domestic enterprises during 2005-2010. The
average ETR of foreign enterprise are still lower than that of domestic
enterprises even after reforms of the enterprise income tax system. On the
other hand, we investigate the relationship between effective tax rates and
corporate characteristics. The empirical results show that firm size and
inventory concentration have significant positive associations with ETR;
state-owned shares, foreign shares, capital intensity, long-term investment, issuing H shares and growth of return on assets have significant negative associations with ETR.