The stretch forming applied force during the forming process and exceed the yield stress of the raw material to make the part deforming plastically, and fitting the contour of a form block, then the purpose of forming can be reasonably achieved. The saddle-shaped skin located in the mating area between the vertical stabilizer and the empennage. This study investigates the stress distribution on the stretch forming of saddle-shaped skins. First, apply the FEM software-ABAQUS to analyses the stretch forming of saddle-shaped skin. Then use the statistical method to analysis the stress in different forming conditions. Finally, the stress of saddle-shaped skins on the critical location is analyzed and discussed. This study aims to modify the process parameters in advance to prevent the failure and defects of skin and provide valuable information for both production engineer and tool designer to improve their design of process parameters and form block.