The optimization of crankshaft should be weight reduction with the satisfation of constraints. Constraints of crankshaft design are safety from stress, torsional vibration and safety from lubrication. This study considers the torsional vibration as critical condition, because the design of vibration damper is not conceptural design but detail design. In order to reduce the calculation time of stress analysis, F.E.M model uses rough mesh with the compensation for the stress concentration. F.E.M model is applied to the remodelling technique which builds F.E.M model from modification of base model. The optimization algorithm in this study employs a hybrid feasible direction method and a hybrid unidirectional method. They may converge rapidly to the optimum in a large-scale structure optimization like crankshaft analysis. The application model is adopted to crankshaft of D2366 turbo engine among D.H.I STORM series.