abtract This paper uses a seasonal dependence VAR model that is proposed by Olivei and Tenreyro in the year 2007.We are to assess whether the effect of a policy exogenous shock differs according to the quarter in which the shock occur. We consider Taiwan as a small open economy with flourishing international trade; the effect of exchange rate is viewed as an important transmission channel in monetary transmission mechanism. First part, we consider domestic monetary policy shock how to influence macroeconomic variables. Second part, the United State is powerful around the world. The Fed policies whether affect Taiwan macroeconomic or not. Finally, discuss an exogenous shock on the exchange rate to impact Taiwan macroeconomic.