Abstract: Crankshaft is the main moving part of diesel engine and other power machinery. Its strength and performance directly determine the life of crankshaft. Because the structure of crankshaft is complex, and many crank parts of crankshaft will bear cyclic stress, the existing mechanical knowledge is difficult to check the strength and evaluate the life of crankshaft. In this study, the crankshaft of EV80 two cylinder diesel engine is taken as the research object. Firstly, theoretical calculation is carried out according to the boundary conditions and ignition conditions of each cylinder; secondly, the actual working conditions are simulated by NASTRAN in NX to analyze the mechanical properties of the crankshaft. Finally, the fatigue strength of diesel engine crankshaft under alternating load is checked and the fatigue life of its parts is evaluated. The results show that:（1） the total displacement and equivalent stress of cylinder 1 are greater than that of cylinder 2, the displacements are 0.089 5 mm and 0.020 7 mm respectively, and the equivalent stresses are 246.55 N and 73.37 N respectively;（2） the displacement changes in X and Z directions are smaller, and the trends of displacement changes in Y direction are the same to that of the overall;（3） the failure fatigue and fracture of crankshaft are located at the fillet of connecting rod journal, and the minimum fatigue strength coefficient is 2.298. The simulation results provide theoretical basis for the subsequent improvement of crankshaft structure.