中文摘要：

利用基于投入导向的数据包络方法，对我国9家主要商业银行2009--2011年的成本效率和投入冗余情况进行研究，结果显示：国有商业银行的成本效率值低于股份制商业银行，其中人员投入冗余是造成商业银行成本无效率的主要原因，绝大多数商业银行的存款投入没有出现冗余情况。

英文摘要：

The paper studies the cost efficiency and the input redundancy of nine domestic commercial banks from 2009 to 2011 years with data envelopment method based on the direction of investment. The study shows that the cost efficiency of state-owned banks is lower than joint-stock commercial banks. The staff redundant input is the main cause of the cost ineffi- ciency of commercial banks and the majority of commercial banks have no redundancy in the deposit input.