A military vehicle undergoes normal to extreme driving conditions, which consequently induce the fatigue and fracture of cabin and frame. So, it is important to estimate the fatigue life of two components at an initial design stage. In this paper, Modal Superposition Method(MSM) was applied to evaluate the durability performance of a small-sized military truck. For reliable durability analysis, a Virtual Test Lab(VTL) Model was established by correlation with experimental results. These data were extracted from actual driving test, modal test, and SPMD(Suspension Parameter Measuring Device) test. This process shows that Virtual Fatigue Analysis can be a useful approach in the development of military vehicles as well as commercial vehicles.