We investigated the effect of carbon nanotube on the crystal structure and mechanical/ferroelectric/piezoelectric properties based on poly(vinylidene fluoride) (PVDF) and carbon nano tube (CNT) composite film. The composite films were prepared by solution blending method, and the films were formed by hot-pressing. The contents of CNT were from 0.001wt.% to 1wt.%. For inducing piezoelectric beta-crystal structure, the hot-pressed nano composite films were drawn by 400% elongation. These samples were poled at high voltage and high temperature for polarization of the PVDF/CNT composite film. The beta-crystalline phase were increased with CNT contents, passing through the peak, and decreased. The structural changes depend on the CNT contents, drawing and poling conditions.