Abstract: Stretchable electronics are mainly composed of the organic substrate and the metal thin conductor attached to the substrate. The geometric parameters of both substrate and metal conductor play an important role in the flexibility of stretchable electronics. In this paper,the effect of geometric parameters(length,width,and thickness of the substrate) on the flexibility of stretchable electronics was studied. The ABAQUS software was used to simulate the uniaxial tensile tests on the polyimide-supported copper conductor to determine the effects of geometric parameters of the substrate on its flexibility. As shown in the results,the effect of substrate length on the deformation of the system is very small; while the increase of width or thickness of the substrate can decrease the substrate deformation but increase the strain of metal conductor. This work can provide a theoretical support for the geometrical design of stretchable electronics.