In the present paper, the unsteady and two-dimensional magnetohydrodyna-mical equations are solved to describe the origin and evolution processes of the galactic magnetic field and galactic shock waves. The initial uniform magnetic field will wind into the spiral structures in the galactic disk, in which the magnetic field and the interstellar gas are frozen together. The influence cf the galactic magnetic field on the formation of the galactic shock wave is analyzed. As the magnetic field is not very strong, the influence is weak.