Particle simulation of ion thruster grids was carried out via particle-in-cell(PIC) method and numerical method for calculating the erosion depth of the accelerator grid downstream surface was developed.Xenon was used as propellant and Molybdenum was used as grid material.Monte Carlo method was adopted to simulate the charge exchange collisions between Xenon ions and atoms.Distribution of erosion depth of the downstream surface of accelerator grid was obtained

and the erosion pattern agreed with the "pits and grooves" erosion pattern.Depth from focus(DFF)method was used to measure the erosion depth of the downstream surface of the accelerator grid and comparison between the measured and calculated erosion depth was carried out.