Piezoresistive sensors made of graphene and PDMS have excellent performance, its piezoresistive response is a crucial index. In this study, a homogenization modeling method is proposed to simulate the piezoresistive behavior of graphene/PDMS composites, and to better analyze the nonlinear response of the resistance of graphene sensor under large deformation. The simulation results show that with the increase of graphene content, the elastic modulus of graphene/PDMS composite increases, and its linear piezoresistive response stage also extends accordingly.