Abstract: Based on the physical law that charged particle experiences Lorentz force in magnetic field,we have analyzed the long-term averaged changes in classical orbital elements with two different charging modes:(1) The spacecraft is charged constantly;(2) The spacecraft is charged in the first half orbital revolution and uncharged in the second half.It is found that,in the first mode,the long-term changes in the longitude of ascending node,argument of periapsis and mean anomaly,can be effectively controlled by Lorentz force,while semi-major axis,eccentricity,and inclination can not be.Meanwhile,the eccentricity can be varied in the second mode.Based on the averaged evolution of the orbital element difference between two spacecrafts in formation-one is charged deputy and the other is uncharged chief,we proposed a new propellantless means for formation control-adjusting the size of fly-around elliptical relative orbit and formation center,when the chief spacecraft's reference orbit is near-circular.The required charge-to-mass ratio for formation control is derived analytically and the effectiveness of Lorentz-force formation control is verified by numerical simulations.