Abstract: In the life test of ion thrusters on the ground, it is very important to find a way of depressing the sputter deposition effect on the ion thruster. In this paper, a mathematical model is built for studying the ion thruster backsputter deposition. The backsputter deposition on LIPS-200 ion thruster under its life test in the TS-7 vacuum chamber is numerically simulated by using this model. The resulted backsputter depositions are 0.79 μm/kh and 0.20 μm/kh for titanium and graphite lining, respectively. Comparing to the backsputter deposition data measured in the life tests for the ion thruster by NSTAR and NEXT of the US, it can be concluded that the backsputter deposition effect on the LIPS-200 ion thruster is in an acceptable level.