This paper structures and estimates an open economy mixed AD-AS model based on statistics from 2002 to 2013 in China, analyzes and compares the optimal monetary policies among three targets, taking interest as policy instrument, deduces the optimal interest rate rule in China with dynamic optimization method. As a result of analysis and calculation, we get the following conclusion:The optimal monetary policy of interest rate smoothing target is more propitious to China, the corresponding optimal interest rate rule could effectively control both of output gap and inflation in the long term, and possess well both of feasibility and operability, this rule could contribute to stabilization of macro economy and society in China.