A computational investigation is carried out in the field of charged-particle optics with the aid of numerical analysis methods and personal computer . The work is concerned with the design of electrostatic lens systems operated under the telescopic mode of operation. The paraxial-ray equation is solved for the assigned trajectory to determine the electrostatic potential and field distributions which satisfy the telescopic trajectory. From the potential distribution and its first and second derivatives, the optical properties such as the focal length and the spherical and chromatic aberration coefficients have been calculated. The electrodes shape of the electrostatic telescopic lens system was then determined. The present investigation is also concerned with the effect of space charge on the design and aberrations of such telescopic electrostatic lens system. The space charge is highly dependent on the value of the electron beam current and it has been found to be an important parameter affecting the geometry of the electrostatic lens system. The results of this investigation not only prove in theory the possibility of designing electrostatic lens systems operated under telescopic condition with low aberrations but also shows the possibility of constructing such lenses in practice.