Fatigue failure is the single largest cause of failures in metal components. Fatigue is a very complicated issue. Fatigue analysis by FEA simulation is a worthy approach for fatigue design. This chapter discusses and explains how to use SolidWorks Simulation to estimate fatigue damage of metal components. First, the fundamentals of metal fatigue are presented, which cover cyclic stress, its descriptions, the definition of fatigue, fatigue damage mechanism, fatigue test, typical S–N curves, modification factors, fatigue strength reduction factor, and the famous Miers’ rule. The purpose of these is to gain a basic understanding of fatigue and be ready to run fatigue analysis by FEA simulation. Then, for fatigue damage analysis in SolidWorks Simulation, the “Static” module is used to run static stress analysis first. Typically, the absolute maximum load is used to run the static analysis to check whether components are safe. This simulation will provide the maximum stress at every point when a cyclic load is estimated. Finally, another “Fatigue” module is used to estimate the fatigue damage. Several examples with step-by-step instructions are provided to demonstrate how to simulate the fatigue damage.