A crankshaft is often designed with a fillet radius to improving fatigue life of crankshaft. The fatigue life of crankshaft is depending on the proper fillet radius. This fillet radius is changes than fatigue life is also changes of crankshaft. In most of the time fatigue failure is occur in crank-pin web fillet region. The crankshaft fillet rolling process is one of the ommonly adopted methods in engineering to improve fatigue life of the crankshaft. A finite element analysis is implemented to approximate the stress distribution induced in the crankpin fillet region. The modelling of crankshaft is created by Creo-parametric. Finite element analysis is performed to obtain the variation of stress at critical locations and fatigue life of the crank shaft using the ANSYS software and applying the boundary conditions. Existing crankshaft results from finite element analysis is comparing with the experimental result after that boundary conditions are satisfied than only changes in model of crankshaft to improvement in fatigue life. This work in doing for optimization of a crankshaft in crank-pin web fillet region with fatigue life as well as to study a relation between fillet radius/diameter of crankpin to fatigue life.