Impossible trinity (the ability to have only two of the three policy goals - the free flow of capital, exchange rate stability and an independent monetary policy) continues to be a model of macro-economic policy. The globalization of the financial markets in 1990-2000 to reduce the stability of the exchange rate and monetary policy autonomy of the countries. An unintended consequence of financial globalization is increasing the cost of loans of developing countries and the debt crisis. Emerging market reaction by selecting the target control the flow of capital in the impossible trinity, integration of their financial market and increase foreign exchange reserves, self.insurance as a means of joining in global finance. This article, the authors use the model impossible trinity by Robert Mundell and Marcus Fleming (Mundell . Fleming model) to explain the objectives of macroeconomic policy in Vietnam for period (1990-2007) and after joining WTO (2007-present). The author updates the experience of countries in the world and lessons for future policy options for Vietnam.