The mechanical response and failure of the specimens of magnesium alloy AZ61 with different heating rates (HR) and loading rates (LR) were investigated by a Gleeble-1500 thermal-mechanical material testing system. It was found that heating rate has markedly effect on the strength and plasticity of the specimens. The higher the heating rate is, the lower the strength and the smaller of the plasticity of the specimens will be. There is the relatively small effect of the loading rates on the strength and plasticity of the specimens. The metallographs of the failed specimens were also observed. It shows that there are many microvoids in the specimens near the fracture sections. These microvoids may come from the local thermal and stress inconsistency under high heating rate and loading rates and degrade the strength and plasticity of the specimens.