碩士 國立臺灣科技大學 資訊管理系 100 This article takes Foreign banks' branches in Taiwan during year 2007 to 2009 as the research subject and introduces data envelopment analysis (DEA) to evaluate the operating performances of business unit of banks to provide the reference for bank's managers in determining operation strategies about before the financial crisis and on then after. The result indicates that, in overall technical efficiency, the case banks has many inefficient branches distinctly; only 36.36% banks can retain overall technical efficiency efficiently, and the pure technical efficiency of banks is 63.63%, which is probably because of scale reallocation too slow or such impact is huge on the asset-return, leading to the above result. The scale efficiency of the case banks during the sample period is 36.36%. The Super-SBM shows 1 case bank has the amazing 68.73 efficiency among all others on 2007. In the Malmquist index, by using BCG-matrix to make easier to look at the result and it shows only 1 bank can keep C