Abstract: The regularity of electron motion with non-circular orbits in an electro-static centrifugal system is investigated. Through extensive numerical computation, analysis and investigation, the following results are obtained: there exist radial and azimuthal perio-dicities in the non-circular orbit motion of electrons in the system and these periodicities are related to the transverse injection velocity and position of the eletrons and the electrostatic voltage applied in the system but have little relation to the transverse injection angle of the electrons; the ratios between the radial and the azimuthal periods of the electron motion under different parameters approach to the same constant; if the injecting transverse electron velocity is less than 0.35c, the radial period of the electron motion is inversely proportional to the square root of the electrostatic voltage applied in the system; and the radial periods of electron motion in the system are equal to those of the corresponding characteristic oscillation of the electrons in the electrostatic centrifugal system.