The crankshaft is an important component of diesel engine. In this paper, a three-dimensional model of a diesel engine crankshaft was established corresponding to the practical conditions by Using PRO/E software. Using ANSYS analysis tool, the finite element analysis for the crankshaft was conducted under extreme operation conditions, and the stress distribution of the crankshaft was presented. The static rigidity and intensity of crankshaft was analyzed in detail. The crank stress change model and the crank stress biggest hazard point were found by using finite element analysis, and the improvement method for the crankshaft structure design was given.