The utility model relates to an unmanned aerial vehicle emergent power -off protection device out of control, including the battery crossover sub, the control modul, the battery crossover sub includes insulating casing, insulating casing includes the casing, an upper cover, the built -in public head of installation in the casing, built -in female head, be equipped with down the baffle between built -in public head and the built -in female head, the baffle will embed the public affairs head and embed female first positive negative pole and separate down, be equipped with a plurality of spring in the casing perpendicularly, on cover and be equipped with two electric conductors, separate through last baffle between two electric conductors, when the upper cover is covered, two electric conductor both ends respectively with built -in public first interface and built -in female first interface connection, upper cover one side is rotated with the casing and is connected, upper cover opposite side outer end horizontal installation iron sheet, the electro -magnet is installed in the casing outside, control module includes protector out of control, data transmission module, the singlechip that connects gradually, and the singlechip is connected with the electro -magnet, the utility model provides an unmanned aerial vehicle problem that can not get back to ground safely under out of control state.