Abstract: Working principle of RIT-15, its performance, parameter calculation and its experiments are presented briefly in the article. The inert gases Xenon(Xe) and Argon(Ar)have been used instead of Mercury(Hg)as the thruster propellant. Experiment results show the thruster has normal operation. Beam current of 150～220mA can be extracted from the source and the correspondent thrust is 7～14mN. Inert gas is a kind of hopeful propellant for ion propulsion because it is convenient in operation and nonpoisonous. But inert gas thruster has lower thrust level and lower mass utilization, these disadvantages could be eliminated with improving the thruster structure and increasing the coupling ability of RF generator.