Abstract: To accurately evaluate the fatigue lives of flexible carbodies under dynamic loading, a full locomotive multi-body dynamic model was established by integrating multi-body dynamic simulation (MBS)and finite element method (FEM).Loading histories at 35 critical positions were calculated, and quasi-static stress analysis method was used to obtain the stresses influence coefficient ( SIC) corresponding to the 35 loading histories.The natural frequencies and modes of vibrations were determined by Modal analysis, and the reduced model of the carbody was derived with substructure technology.Fatigue simulation was finally done based on stress distribution, stress-time histories, and Palmgren-Miner damage theory.In the simulation, the safety factor technology in die software FE-FATIGUE and the wave analysis for fatigue and oceanography (WAFO) tool in MATLA were utilized.Simulation results include predictions on damages and fatigue life.