Stress of mechanical components can be induced by external forces or/and by a change in temperature. Thermal stress of a component is induced when the component cannot be freely expanded or contracted upon a temperature change, or when there is a non-uniform distributed temperature. This chapter discusses and demonstrates how to obtain a temperature distribution and then how to simulate thermal stress by SolidWorks Simulation. For thermal stress analysis, we must use the “Thermal” module in SolidWorks Simulation to obtain the temperature distribution under thermal loads. Then, we need to use the “Static” module to run a thermal stress analysis, where the temperature distribution obtained will be used as a thermal load for thermal stress analysis. In this chapter, we will first discuss the three heat transfer mechanisms: conduction, convection, and radiation. Then, the general procedure for thermal analysis is presented and explained in detail. Examples of steady thermal analysis and transient thermal analysis are presented to demonstrate how to use the “Thermal” module to run thermal analysis. Finally, we use the “Static” module in SolidWorks Simulation to run thermal stress analysis, where the temperature distribution is used as thermal load.