Abstract: The managedfloating exchange rate system is one of special manifestations of target zone system,and actually it is a quasi-target zone system. Hence RMB equilibrium exchange rate may be estimated by use of the method of exchange rate target zone model. At present, the sticky-price model is one of best models, and it is a extension of flex-price model. The model is based on assumptions of price inertia and output decided by demand. Under those assumptions and the condition of the commodity and the currency market equilibrium, a stochastic differential equation may be established, and in the light of theequation,we may get a exchange rate function. Our research indicates a good outcome may be made,applying the sticky-price model to estimate RMB equilibrium exchange rate.