Magnesium and its alloys are potential biodegradable materials for their outstanding biological performance. In recent year, much attention has been paid on biodegradable magnesium alloys. The corrosion behavior of AZ31 magnesium alloy was investigated using in as-received (AZ31-AS), solid solution (AZ31-SS) and precipitation treated (AZ31-CP) conditions in 0.9wt.% NaCl solution by open-circuit potential and potentiodynamic polarization tests. The results show that the average degradable rate of AZ31-SS sample is lower than that of both AZ31-AS and AZ31-CP samples. In addition, the surface of AZ31-SS sample after dynamic polarization test is smooth, while the surface of both AZ31-AS and AZ31-CP samples show pitting.