Since 2003，under pressures exerted by relevant U.S.interest groups and the U.S.Congress，RMB exchange rate issue has been politicized a controversial focus in the U.S.-China relations. The politicization of RMB issue was caused by constituency politics in the U.S.Congress，given the roles played by the Congress in the process of U.S.trade policy making. The purpose of a U.S.legislator to propose a RMB legislation was not to make it become a law，but to brandish it as a“threat”，to put pressure on the Executive and claim credit from his/her constituencies，and get his/her upmost goals：maintaining and enhancing political standing at home and in Washington and seeking re-election. Recognizing the essence of politicization of RMB issue is important for us to respond properly the pressure brought by the U.S.side. Meanwhile，different voices on RMB issue from both the U.S.and China are believed to help to come to a reasonable solution to the issue.