The revolution of RMB exchange rate formation mechanism in July, 2005 results in structural changes in RMB exchange rate, which represents the direction to marketization and makes base for RMB equilibrium exchange rates. In this context, this paper uses econometric model to examine the validity of PPP between RMB and other currencies and to calculate the half life of purchasing power parity deviation. The results show that weak form of PPP is held between INR/RMB, ZAR/RMB, and KRW/RMB. But the strong form is not supported. The half life calculated in this paper shows different results.