Information system is widely used in financial area all around the world today, and business intelligence systems has draw more and more attention from both academia and business circles. Based on this situation, we carried out our research. The main purpose of our research is to find out how Decision Support System (DSS) is used in China's banks. As there are more than five hundred banks in China, we choose the four biggest commercial banks(which has cover more than 85% of financial activities in China's banking area) as examples to study. We sent Emails and made telephone calls to different roles in these four banks, from chief information officer, managers of business to normal staff. Before carried out interviews, we did literature study to set a scientific background for our interviews. After the collection and analysis of data from both interview and literature study, the result is presented in three chapters. The theoretical study part introduces the theory background of DSS and how it is used in banks, the framework of the DSS and the basic model of the DSS, also new techniques in DSS. The Empirical results part introduces the results got from interviews. In Analysis part the results from the former chapters will be combined and analyzed, in this part we presents the application situation of DSS in China's banks, the affection of DSS on banks employees and improvement and drawback DSS brings to China's banks. Also new technology of decision support system and its application. And the last part we would draw conclusions for this thesis and summarize results from the interviews and theories and evaluate the whole research process. And the introduction of our research and the methods used to achieve the research goal will be introduced in the first two chapters.