Abstract: Aimed at the effect of cold expansion on the initiation and propagation of fatigue crack of alloy 6005,the fatigue life improvement of the damaged structures after the cold expansion process was investigated with the single edge pre-cracked specimens.The numbers of cycles to obtain a new crack initiation are analysed from the different cases.A numerical investigation with ANSYS code is conducted to determine the residual stress field and the size of the plastic zone generated by the cold expansion ,the influence of the degree of cold expansion on the different parameters shows that the maximum value of residual stress is localized between 1 and 1.1 of the yielding stress for any value of the diameter of the hole and of the degree of cold expansion,and the DCE has a remarkable influence on the size of the zone of compressive residual stresses and on the size of the zone of plastic deformation.