Abstract: To investigate the factors that affect the ground testing consistency of the LIPS-200 ion thruster and to better understand its working mechanism, the influence of vacuum degree and working fluid flow rate on the electrical parameters of the LIPS-200 ion thruster was studied experimentally to obtain its sensitivity to vacuum degree and working fluid flow rate variation. The results show that when the vacuum degree changes from 2×10^-3 Pa to 1×10^-2 Pa, the variation of beam current is about 1.7% of the rated beam current, whereas the acceleration current increases by three times. When the neutralizer flow rate is changed, the beam current and anode voltage remain almost unchanged. The anode voltage decreases when the anode and the main cathode working fluid flow rate are increased. The beam current gradually increases with the increasing anode working fluid flow rate, while decreases with the increasing main cathode working fluid flow rate. The results may serve as a reference to improve the consistency of ground testing and to optimize the settings of working conditions for ion thruster experiments.