Poly(vinylidene fluoride) nanofibrous membranes with high porosity, large electrolyte solution uptake, and adequate mechanical properties were prepared by electrospinning. The physical properties of the electrospun poly(vinylidene fluoride) membranes can be improved by thermal treatment. Results showed after the thermal treatment, there had appeared ever-increasing tensile strength and elongation of the poly(vinylidene fluoride) membranes. The crystal structures of poly(vinylidene fluoride) fibers were greatly improved.