To obtain the behaviors of Poly(vinylidene difluoride) (PVDF) under large tensile deformations, this paper investigates the tensile behavior of a single molecular chain of rod-like PVDF with β phase structure at zero temperature using a Density Functional Theory (DFT) calculation. We obtain the critical bond length, critical fracture energy, critical tensile force and the elastic constant when the β phase PVDF chain is stretched to break. Then a novel method is proposed to build the cell model of the amorphous polymer, which is used for the molecular dynamics (MD) simulations of uniaxial tensile of PVDF. During the simulations, two cases that the chains will never break and are permitted to break are considered. In the first case, the simulations with three different strain rates 10¹⁰ s-1, 10⁹ s-1, and 10⁸ s-1 were carried out and the strain rate dependence of the stress-strain relationship, the structure deformation were analyzed as well. In the second case, the simulations with a strain rate of 10⁹ s-1, 5×10⁸ s-1 and a quasistatic strain loading were performed and the stress-strain relationship, the cell structures before and after the breaking were researched. Some key factors to influence the simulation results and some important deformation information were analyzed. This is helpful to elucidate the inherent deformation mechanisms during the tensile procedure.