Abstract: This paper uses cointegration techniques to analyzes the logical link between RMB exchange and export cost in China in the reform period. A possible long-run equilibrium relation between these variables is studied. Error correction model(WCM) which describes the mechanism of adjustment to long-term equilibrium is built. We test the stability of ECM as well. The possible new relation between RMB exchange rate and export cost, which was based on the empirical analysis, is considered under the new exchange rate regime. In the end of this paper, the conclusions are given.