Abstract: The neutralizer based on the grid-controlled thermal cathode does not consume propellant,which can simplify the micro-electric propulsion gas supply and power supply system,reduce the complexity of the entire system,and increase the specific impulse of the thruster.In order to study the influence of the structure size and operating parameters of the neutralizer on the electron emission performance,the Opera simulation software was used to model the neutralizer,and the influence of the main design parameters on the anode current,grid intercept current and electron beam trajectory was analyzed.The analysis shows that the anode current of 24.6 mA can be drawn with reasonable design parameters,and the intercepted current of the grid is 0 mA,which can meet the needs of the micro electric thruster for the neutralizer.The simulation analysis results for the optimization of the structural size design of the neutralizer also provide a basis for subsequent test verification.