Bolt fatigue failure brings about critical damage on the jointed parts unexpectedly. Therefore it is important to minimize the possibility of bolt fatigue fracture when designing the structure. According to the VDI2230, bolt fatigue failure is evaluated by the alternating axial stress which comes from repetitive external force. The external axial force is distributed proportionally to the bolt and jointed part according to their relative stiffness, respectively. Bolt shape is directly correlated to the bolt stiffness. This paper shows the way to minimize the external force on the bolt by controlling the bolt shape, with finite element method and equations. M6 tapped threaded bolt is used and dynamic load is applied on the bolt concentrically.