The present disclosure discloses a rotary joint electromagnetic locking device and a rotary joint, the rotary joint electromagnetic locking device comprising a first electromagnetic sucker, a sliding plate, a rotary plate, a connecting shaft connecting the first electromagnetic sucker and the sliding plate, and a second electromagnetic sucker, different from the prior art. When the first electromagnetic sucker and the second electromagnetic sucker have no adsorption force, the sliding plate and the rotary plate can be locked to each other; when the second electromagnetic sucker has an adsorption force, the rotary plate or the first electromagnetic sucker is adsorbed by the second electromagnetic sucker, making the sliding plate and the rotary plate to be further locked; when the first electromagnetic sucker has an adsorption force, the sliding plate can be adsorbed to the first contact surface of the first electromagnetic sucker, making the sliding plate released from the rotary plate.