Abstract: Grid is one of the important components for ion thruster.When the thruster operating,deformation will be taken place and even be destroyed with asymmetric distribution of temperature.It is necessary to analyze and calculate its thermal stress for selecting optimal structure and materials.A numerical model was established for analysis the grid thermal stress.The Ti grid thermal stress of 20 cm Xenon ion thruster was calculated.It was confirmed that Ti grid structure and parameter were fit for condition of thermal stress.