The microstructure, mechanical properties and corrosion of Mg-2.4Zn-0.8Gd (wt.%) alloy with and with-out solution treatment before extrusion were investigated in vitro. The volume of secondary phasesdecreased after solution treatment, leading to more homogeneous microstructure distribution of as-extruded samples. The solution treatment before extrusion contributed to an elongation increase by 24%,and corrosion resistance was improved by about 20% according to hydrogen evolution and weight losstest. Electrochemical test also confirmed the improvement of corrosion resistance. With solution treat-ment before extrusion, the corrosion morphology was transformed from localized pitting corrosion touniform corrosion due to the more homogeneous microstructure.