Abstract: As one of the planets in the solar system,the study of Mars’magnetic field,atmosphere,climate,composi-tion and topography is conducive to the development and utilization of space resources.CO₂is the main component of Mars atmosphere.The study of electric propulsion technology using CO₂as propellant can be of great significance to Mars exploration and other deep space exploration.In this paper,the CO₂RIT’s ion source was used as the research object.First,the ignition experiment of the CO₂RIT’s ion source was carried out.Next the plasma parameters in the discharge chamber were diagnosed by Langmuir probe,and the results were compared with those in Ar,which is the common propel-lant used in ground experiment.While the influence of RF power on plasma parameters in CO₂is also studied.Then a DC voltage was applied to the grid system to study the beam.The influences of screen grid voltage,RF power,mass flow rate and grid transparency on the grid current of the thruster’s ion source were analyzed.