Thermomechanical treatment was adopted to improve the comprehensive performance of AZ80 magnesium alloys in this paper. The influence of varying the thermal processing parameters and deformation on the microstructure and mechanical properties of AZ80 magnesium alloy was studied, and the optimal process of themomechanical treatment was obtained. The experimental results show that the hardness increased with the increasing of deformation and the hardness is up to the peak value with 30% deformation. After aging, the hardness measurements and microstructure analysis results show that the hardness increased with increasing aging temperature, and reached the peak value at temperature 170°C, while the hardness decreased sharply when the temperature goes beyond 170°C. After thermomechanical treatment, the grains of AZ80 magnesium alloy became uniform and fine. The roles of both deformation strengthening and dispersion strengthening were to improve the mechanical property of AZ80 magnesium alloy.