To enhance the long-distance transmission performance of electron beams in space experiments, this paper presents the design of a compact beamline structure composed of three quadrupole magnets and one solenoid. A beam transmission model was established based on the beam transfer matrix theory, and the NSGA-II algorithm was employed to perform multi-objective optimization of the magnet parameters, achieving synergistic control of beam spot expansion and divergence angle suppression. Optimization results demonstrate that within a transmission distance of approximately 2 m, this structure can expand the initial millimeter-scale electron beam to within 0.03 m, while simultaneously increasing the proportion of electrons with a divergence angle less than 0.05 mrad from 3.54% to approximately 55.6%. The beamline exhibits excellent transmission stability, providing an effective solution for electron beam engineering applications in complex magnetic field environments.