According to the performance parameters and structure position of the design target, the initial value of the gun is obtained by the comprehensive iteration method. Moreover, the performance of tungsten and LaB6 cathode materials was compared, the appropriate cathode materials were selected, and the 60 kV space electron gun was simulated by using the SOURCES related procedures, and the simulation results such as coefficient of chromatic aberration and beam spot diameter were obtained. According to the focal length formula, the focal length of the first-order focusing system is obtained and the simulation results of the focusing system, such as focal length, beam spot and optical path diagram, are obtained. By analyzing the shortcomings of the first stage focusing system, the second stage focusing system is redesigned, and the performance parameters such as pole shoe hole diameter, coil excitation and the distribution map of the electromagnetic lens axis are obtained by simulation. Finally, the parameters of electron gun and electron optics are obtained according to the simulation results of two-stage focusing system.