To study how to relieve the inflation pressure by monetary policy in China，we consider two important characters influencing the policy choice in Chinese economy，one is that China is an open economy，the other is duality structure of state-owned enterprises and non-state-owned enterprises. Then we extend the optimal monetary model with these two restrictions and add exchange rate objective in objective function. Using the econometric method of Johansen Co-integration test and Autoregressive Distributed Lag model，we show the empirical results for the restrictive functions. By analyzing the relations between policy variables and economic behavior variables，we give some suggestion for monetary policy to control inflation rate.