Abstract: To study the kinetic characteristics,the motion of the LEO electrodynamic tethered (EDT) propulsion system ismodeled, in this paper, from the angle of mechanics andelectrodynamics. The numerical solutions under various initialconditions are obtained,based on which the motion of space EDT system is discussed. The effects of Ampere force, the tether's deformation and deflexion, on the orbital plane, as well as on the orbital altitude, are studied. In addition, the efficiency of space EDT system and the effect of the earth's rotation are evaluated.