This work addresses the problem of fatigue strength prediction of crankshaft fillet rolling processes, to reduce friction losses, weights and material costs. It is usually assumed that the effect of fillet rolling process on crankshaft fatigue are conservative and empirically. A predicting method of fatigue strength for ductile cast iron crankshafts is presented, in which the rolling process is considered. The method including two parts: modelling of crankshaft fillet rolling dynamic and predicting fatigue strength of rolling process. The rolling process is solved with an implicit arithmetic and validated by the measurements and tests. Based on the crankshaft dynamic loads calculated by AVL/EXCITE Power Uint, the fatigue effect factors are considered, consisting of compressive residual stresses, work hardening, and reduction of the roughness. The predicting method is applied on a 1.5l I4 gasoline engine. Compared with a crankshaft bend fatigue test, the results show that the method is effective.