Abstract: In order to improve the performance of quadrupole mass spectrometer, it is necessary to model, simulate and analyze the mass spectrometer in advance to ensure better design parameters under engineering constraints. For the spaceborne quadrupole mass spectrometer, based on the theory of ion motion in quadrupole electric field and collision between ion and neutral gas, the electric field distribution and ion motion state are modeled and simulated by advanced multiphysics field simulation software COMSOL. By analyzing the simulation results, the effects of the changes of related parameters on the sensitivity and resolution of quadrupole mass spectrometer are obtained. The results show that the simulation model can well simulate the ion motion state, analyze the performance changes of quadrupole mass spectrometer, and provide a reference for the improvement of the project.