Tensile behaviors of an AZS0 alloy were investigated by elongation-to-failure tensile tests at 300, 350, 400 and 450 ℃, and strain rates of 10-2 and 10-3 s 1. Strain-rate-change tests from 5×10-5 s-1 to 2x10-2 s-1 were applied to study deformation mechanisms. The experimental data show that the material exhibits enhanced tensile ductilities of over 100% at 400 and 450 ℃ with stress exponent of 4.29 and activation energy of 149.60 kJ/mol, and initial fine grains preserve in evenly deformed gauge based on microstructure studies. The enhanced tensile ductilities are rate controlled by a competitive mechanism of grain boundary sliding and dislocation climb creep, based on which a model can successfully simulate the deformation behavior.