Abstract: In order to provide theoretical basis for the design verification and improvement of the melting electron gun, the CST particle studio is applied to simulate some type of generating system of melting electron gun. The perveance, the beam flow pattern, and the minimum bunch flow diameter (waist) of the electron gun are obtained at the acceleration voltage of 30 kV and a cathode/anode radius of curvature ratio for 2.2.The comparison of simulation result and theoretical calculation shows that both are approximately equal within the allowed error range.