Abstract: The ion thruster is a crucial power device used extensively in various space missions. Numerical simulations have played a significant role in understanding the physical mechanisms and aiding in the design of ion thrusters and have become an indispensable research method for studying ion thrusters. To foster the innovative development of ion electric propulsion technology and ensure that ion thrusters continuously meet the demands of current and future space missions, a comprehensive review of the development and application of the Particle-in-Cell（PIC）model in numerical simulations of ion thrusters is presented. A detailed summary of the advancements and achievements in both full and hybrid PIC models for the discharge chamber, grid system, plume region, and integrative simulation of ion thrusters is provided. In response to the need for numerical simulation research on ion thrusters, the future development directions of PIC models are identified. These directions offer theoretical support and optimization guidance for the progress of ion propulsion technology.