Abstarct: Shot peening is a well-known process to improve fatigue life of various mextallic components. This process lead to producing compressive residual stress near the surface of components that is beneficial to preventing initiating surface cracks and resistance to stress corrosion cracking. Peen forming is a method that is derived from shot peening and major application of this process is in aeronautic industries to produce large thin components with gentle curvatures such as aircraft panels and wing skins. This process can be divided into two categories; conventional peen forming and stress peen forming. In this thesis, numerical and experimental study of shot peening process and peen forming process with and without elastic pre-strain of sheet mextals were conducted. In order to perform experimental tests, steel shots with 0.4 mm and 0.6 mm diameter and aluminum alloys Al 7075-T6 and Al 6061-T6 strips was used. In addition, for applying elastic pre-strain, fixtures with four different pre-bending radii ∞, 500 mm, 375 mm and 250 mm were designed and manufactured. In numerical section, using same parameters as applied in experiments, first by using a 3D model with random distribution of shot, shot peening process is simulated and then employing this model, peen forming and stress peen forming were simulated in a three step procedure. In the first step, using implicit solver of Abaqus software, pre-bending moment is applied onto an aluminum block in order to produce elastic pre-strain. Then by in an explicit analysis, shot impacts onto an aluminum block with elastic pre-strain were simulated and the induced stress distribution inside block was obtain. Finally, in another implicit analysis, applying the reaction stretching forces and bending moments obtained from previous step, aluminum sheet mextal forming is simulated. Results of experimental and numerical simulations were compared. The results shows that with same peening parameters, compared with conventional peen forming, stress peen forming produces larger curvatures in sheet mextal. Furthermore, with increasing pre-bending moment (reducing pre-bending radius), the resultant curvature in the sheet in the direction of the applied pre-bending increases.