A novel dynamic cold expansion method based on electromagnetic load was developed to enhance the fatigue life of open hole structures. The experiments were conducted to investigate the method, and the corresponding static cold expansion method was also investigated as comparison. The expansion resistance was evaluated. The geometric dimension varieties of holes after cold expansion were measured. Moreover, the fatigue life of specimens after both methods were assessed, and the fatigue failure and fatigue life enhancement mechanisms were discussed. The results show that dynamic cold expansion can obviously reduce expansion resistance compared with static cold expansion and generate more uniform hole diameter distribution along the hole axial direction after cold expansion. In fatigue tests, specimens worked by dynamic cold expansion method exhibited the higher fatigue life than that worked by static cold expansion method, especially under high load level. Furthermore, through fatigue fracture observed dynamic cold expansion specimen will often appear many fatigue source, general along the horizontal direction and the fatigue crack propagation, and the tradition of cold expansion specimen fatigue crack initiation in the entrance of mandrel and extend to the exit, that along the axial dynamic cold expansion method could get more even than the static methods of residual stress, therefore, the fatigue life of the open hole structure is improved.