A large-scale, direct computational model of crankshaft system was established for dynamics simulation and calculation of fatigue life of a crankshaft. The dynamics model was solved by use of high-performance-computing (HPC) technique and explicit finite element method. The calculation result describes the crankshaft dynamics characteristics including strength and distortion in detail. The fatigue life evaluation on crankshaft was accomplished by S-N analysis method straightly utilizing dynamics simulation result and the analytical result based on dynamic stress-time history makes it more reasonable. The computational process and calculation result prove the feasibility and validity of this method for a crankshaft system.