The key objective of this research paper is to investigate the main causes of Vietnam's macroeconomic instability over the period 1986-2013 and recommend some suitable solutions for Vietnam in the future. Key findings are as follows: Two main cause groups of Vietnam's macroeconomic instability, namely the significantly inappropriate macroeconomic policies and poor management as well as the significantly exogenous shocks (such as big net capital inflows to Vietnam, significant investment spending, ...) caused the large macroeconomic imbalances, including the internal and external imbalances (that are not financed in the sustainable way), and consequently resulted in the high macroeconomic instability in both the periods in Vietnam.