The invention relates to a method and a device for electromagnetic continuous casting of bimetallic multilayer round billets. The method comprises the following steps: sending a dummy ingot device into an outer crystallizer to tightly contact with the bottom end of an inner crystallizer, pouring outer layer molten metal to an annular space formed by the inner crystallizer and the outer crystallizer, the outer layer molten metal being cooled by the outer crystallizer, and forming a semi-solid support layer after contacting with the outer circular side wall of the inner crystallizer, the outer circular side wall being bare outside, the dummy ingot device beginning to move downward, casting inner layer molten metal to the inner crystallizer, the inner layer molten metal being cooled by the inner crystallizer and contacting and combining with the semi-solid support layer of the outer layer molten metal to form a compound interface, when a continuous casting process enters a stabilizing stage, switching on a pulse power supply and an intermediate frequency power generator, a pulse field coil applying a pulse electromagnetic field in the inner crystallizer, and an intermediate frequency field coil applying an intermediate frequency electromagnetic field in the outer crystallizer. The method is simple in process technology, an inner layer metal solidification structure and an outer layer metal solidification structure of a manufactured product are refined, surface quality of the outer layer metal is high, and the compound interface is clear and stable.