A homopolar DC electromagnetic transmission, comprising two rotors, a stator and a regulation and control system, wherein each rotor has at least one axisymmetric rotor magnetic and electric conductor, rotor electric conductors and a rotation shaft; the stator has at least one DC magnet exciting coil wound around an axis of a rotation shaft; a main magnetic circuit is guided to be a closed loop by axisymmetric magnetic conduction structural members on the rotor and the stator; at least two main magnetic circuits pass through the rotor magnetic and electric conductors and through stator magnetic and electric conductors; a closed main current circuit is constructed on the two rotors and one stator and is connected in series with all the rotor magnetic and electric conductors, rotor electric conductors, a connecting region clearance between the rotor and the stator, stator electric conductors (6, 11) and stator magnetic and electric conductors; wherein two sides of each rotor magnetic and electric conductor are respectively connected to one rotor electric conductor in an axial direction; each rotor magnetic and electric conductor on the two rotors is interference fit with a rotation shaft, and the rotor electric conductors connected to the two sides of each rotor magnetic and electric conductor on the two rotors are in interference fit with a rotation shaft; the rotation shafts guide a magnetic flux (Φ1,Φ2,Φ3,Φ4) of the main magnetic circuits and the magnetic flux (Φ1,Φ2,Φ3,Φ4) of the main magnetic circuits is connected to a magnetic flux (Φ1,Φ2,Φ3,Φ4) passing through the rotor magnetic and electric conductors; each rotor electric conductor forms a main circuit connection with one of the stator electric conductors (6, 11) through a liquid metal in the connecting region clearance; the connecting region clearance is provided between the rotor electric conductor and the stator electric conductor; the rotor electric conductor and the rotor magnetic and electric conductor adjacent thereto are the same in outer diameter; and the main current direction of each rotor magnetic and electric conductor is mutually perpendicular to the direction of the magnetic flux (Φ1,Φ2,Φ3,Φ4) passing through the rotor magnetic and electric conductors in a meridian plane. the stator has at least one DC magnet exciting coil wound around an axis of a rotation shaft; a main magnetic circuit is guided to be a closed loop by axisymmetric magnetic conduction structural members on the rotor and the stator; at least two main magnetic circuits pass through the rotor magnetic and electric conductors and through stator magnetic and electric conductors; a closed main current circuit is constructed on the two rotors and one stator and is connected in series with all the rotor magnetic and electric conductors, rotor electric conductors, a connecting region clearance between the rotor and the stator, stator electric conductors (6, 11) and stator magnetic and electric conductors; wherein two sides of each rotor magnetic and electric conductor are respectively connected to one rotor electric conductor in an axial direction; each rotor magnetic and electric conductor on the two rotors is interference fit with a rotation shaft, and the rotor electric conductors connected to the two sides of each rotor magnetic and electric conductor on the two rotors are in interference fit with a rotation shaft; the rotation shafts guide a magnetic flux (Φ1,Φ2,Φ3,Φ4) of the main magnetic circuits and the magnetic flux (Φ1,Φ2,Φ3,Φ4) of the main magnetic circuits is connected to a magnetic flux (Φ1,Φ2,Φ3,Φ4) passing through the rotor magnetic and electric conductors; each rotor electric conductor forms a main circuit connection with one of the stator electric conductors (6, 11) through a liquid metal in the connecting region clearance; the connecting region clearance is provided between the rotor electric conductor and the stator electric conductor; the rotor electric conductor and the rotor magnetic and electric conductor adjacent thereto are the same in outer diameter; and the main current direction of each rotor magnetic and electric conductor is mutually perpendicular to the direction of the magnetic flux (Φ1,Φ2,Φ3,Φ4) passing through the rotor magnetic and electric conductors in a meridian plane.