Abstract: The ASDEX ionization gauge is widely used in nuclear fusion devices because of its special electrode structure, which can work in the complex environment of fusion with high magnetic field and high temperature plasma. Based on the simulation methods of Monte Carlo and electron path integration, the effects of magnetic field environment and electrode voltage on the sensitivity and electron motion trajectory are investigated respectively. It is shown that as the accelerating gate voltage increases from 160 V to 430 V, the sensitivity and the average electron track length first increase and then decrease. As the control electrode voltage increases from 75 V to 180 V, the sensitivity increases and then decreases continuously, and the electron divergence first decreases and then increases.The electron collection rate of each electrode under the magnetic field changes sharply with the increase of magnetic induction intensity and stabilizes after 0.1 T. When the magnetic induction intensity reaches 0.1 T, the sensitivity decays slowly by 20% as the magnetic field offset angle increases from 0° to 30°. If the magnetic field offset angle exceeds 30°, the attenuation amplitude of sensitivity increases rapidly.