Abstract: Based on numerical simulation and experimental methods, the metrological performance of the hot cathode ionization gauge is studied, and the effects of electrode voltage and grid structure on the sensitivity of the ionization gauge are analyzed. The research shows that with the increase of cathode anode voltage difference from 50 V to 140 V, the sensitivity continues to increase and then decreases slowly. With the increase of grid wire spacing from 2 mm to 3.5 mm and wire diameter from 0.4 mm to 0.2 mm, the sensitivity increased significantly. The structural and electrical parameters of the ionization gauge are optimized by orthogonal analysis to improve the sensitivity.The results show that when the grid wire diameter is 0.2 mm, the wire spacing is 3.5 mm, the anode voltage is 220 V and the cathode voltage is 80 V, the sensitivity of the hot cathode ionization gauge is the largest. The simulation result is 0.184 Pa^-1, the experimental verification is carried out according to the optimization results, the experimental result is 0.196 Pa^-1. The experimental results are consistent with the simulation results.