Finite element mode was carried out for ultra-high cycle fatigue specimens of SMA490BW steel butt joints used in bogies. Finite element software ABAQUS/ FE-Safe was used to calculate the influences of different arc transition radius r and weld toe angles θ on joint stress concentration factor Kt and joint fatigue life N. The results show that r and θ have significant influence on the Kt and fatigue life of the SMA490BW steel butt joint for bogie. For the same inclination angle θ, Kt decreases gradually with r increasing. With θ increases, the effect of r on Kt is increasing continuously, also the effect of change in Kt caused by r on fatigue life N is increasing continuously. While in the case of same weld edge r, Kt increases with θ increasing. With r increases, the effect of θ on Kt is decreasing constantly, the effect of change in Kt caused by θ on fatigue life N is decreasing constantly. The fatigue performance of SMA490BW steel butt joint was tested by ultrasonic fatigue test machine. The results between the fatigue test and calculation is less than 15%. The finite element calculation result has important significance for improving the fatigue life of welded butt joint for bogie.