Abstract:  In order to evaluate the lifetime of 30cm ion thruster，the thruster lifetime prediction method based on finite life test and simulation model was proposed.The grid hole sputtering erosion model was established by PIC-MCC method.The lifetime prediction research of 30cm ion thruster was carried out.The grid hole etching rate，electric field and ion extraction characteristics were analyzed，and the lifetime prediction value was given.The simulation results are in good agreement with measured values，and the error is less than 20%，which shows the modification of the model based on the measured values of grid holes in each life test section is effective.According to the simulation results，the deceleration grid is the first to fail after the 10000h life test.The estimated lifetime of 30cm ion thruster under the maximum（3kW）condition is 36000h，which can meet the long-lifetime requirements of the electric propulsion system for the small celestial body exploration mission.

Key words: deep space exploration, ion thruster, lifetime, PIC-MCC, grids