Starting method of magnesium electrolytic cell

The invention relates to a starting method of a magnesium electrolytic cell. Specifically, the bottom of an electrolysis chamber (1) in a multipolar magnesium electrolytic cell and the central section of a magnesium collection chamber (2) are respectively provided with a set of AC (alternating current) electrodes (4), and the two sets of electrodes are separately controlled. When the electrolytic cell is started, electrolyte prepared in advance is added to submerge the AC electrodes (4) located at the bottom of the electrolysis chamber (1), so that alternating current of the electrodes is to be delivered. The electrolyte is added continuously until reaching a position of 50mm-60mm below a cathode (3) bottom, and is heated to a temperature of 680-700DEG C and maintained at a constant temperature for more than 4 hours. Then, the electrolyte is added to a standard liquid level (5), and when the AC electrodes (4) located at the central section of a magnesium collection chamber (2) are submerged by the electrolyte