Solidification microstructure of AZ61 magnesium alloys with different electric-magnetic fields was studied. It was found that solidification microstructure of magnesium alloys were equiaxed grains and the Mg-Al-Zn compound phases appeared as meshes on grains boundaries under magnetostatic filed. Solidified under the magnetostatic-power current field, the microstructure was mainly consisted of equiaxed grains similar to that under the magnetostatic field. But the grains were refined obviously and the mesh structure of compound phases became fine due to the applied power current; while in the solidification process of Mg alloys under the magnetostatic-direct current field, the solidification microstructure was mainly rosette grain and purified significantly; the mesh structure of the compound phases disappeared entirely and they were distributed as discontinuous ribbons and spots; they were the results of the directional force inside melts caused by the combination fields.