The real effective exchange rate, as an important indicator for measuring the competitiveness of a national monetary in international trade and finance sector, is playing an increasingly important role in the international financial system of currency diversity. To measure and analyze the real exchange rate of RMB can help us to seize the real trend of the RMB in the international market. Based on a review of related literatures, we measure the real effective exchange rate of RMB from 1980 to 2009, which is based on the weight of time-varying, and analyze the changing trend of the real effective exchange.