Abstract：The ingot of AZ80 magnesium alloy was sawed into sheets of 8mm in thickness, then cut into strips of 120mm long and 5mm wide. Applying different electromagnetic fields, AZ80 magnesium alloy strips were heated to 660℃ in the resistance furnace. The influence of electromagnetic fields on the solidification structure of the AZ80 Mg alloy was examined. It is found that the grain becomes finer and the size and amount of inclusions are reduced in the sample with the AC magnetic field compared to the sample without the magnetic field. The grain sees no significant change in the DC magnetic field. The electron microprobe analysis shows that the Al and Zn contents inside the grain are increased.