Abstract: In order to study the effect of forging temperature on the microstructure and properties of magnesium alloy for automobile, the microstructure, corrosion resistance and mechanical properties of Mg-7Al-3Sn magnesium alloy at different initial and final forging temperatures were tested under the constant preheating temperature of the anvil and forging deformation amount during the forging process. The results show that the average grain size is the largest and the corrosion resistance and mechanical properties are the worst at the initial forging temperature of 420 ℃ and the final forging temperature of 300 ℃. When the initial and final forging temperature is 470 ℃ and 340 ℃, respectively, the average grain size of the sample is smallest, and the corrosion resistance and mechanical properties are best. Compared with those of the samples of 420 ℃ initial forging and 300 ℃ final forging, the average grain size of the samples at 470 ℃ initial forging and 340 ℃ final forging decreases by 64.1%, the corrosion potential increases by 12.5%, the tensile strength increases by 23.7%, and the yield strength increases by 23.1%. Mg-7Al-3Sn magnesium alloy has good corrosion resistance and mechanical properties when it is initially forged at 470 ℃ and finally forged at 340 ℃.