Abstract: In order to study the optimal design method of the grid controlled thermal cathode neutralizer,the Opera simulation software was used to carry out the simulation evaluation of the grid controlled thermal cathode neutralizer,and the designed grid controlled thermal cathode neutralizer was carried out performance test.The research results show that the simulation results are in good agreement with the experimental results,and the anode current are related to the cathodeanode spacing,cathode-grid spacing,grid voltage,and grid hole radius.When the cathode-anode spacing is 5~30L₀,the cathode-grid spacing is D₀~2D₀,and the grid hole radius is 6~8r₀,the electron emission performance of the grid-controlled thermal cathode neutralizer has an optimal point.When the grid voltage is 100 V and the anode voltage is 300 V,the anode current reaches 17.74 mA,the grid intercept current is only 0.03 mA,and the cathode heating power is 8W.