Abstract: Beam distribution is an important technical parameter to indicate the performance of ion thruster,it directly influences the working stability and reliability of ion thruster.Aiming at the problem of spark down of the ion optics system for 30 cm Xenon ion thruster because of the beam distribution imbalance,the cathode baffle test was developed and the relationship between the cathode baffle and the beam distributions was observed.The influence of fore-and-back setting cathode baffle and setting different types cathode baffle on the discharge chamber performance were researched.The results showed that setting cathode baffle could effectively improve beam distributions of the ion optics system,and the working stability of the ion thruster.The anode voltage and discharge loss was enhanced after setting cathode baffle in the high power mode,and with the diameter of the cathode baffle's increasing.Above research will certainly provide technical guidance for improving working stability for the 30 cm Xenon ion thruster.