Poly(vinylidene fluoride)(PVDF)/multi-walled carbon nanotube(MWCNT) nanocomposites were pre-pared by means of ultrasonic dispersion method. X-ray diffraction(XRD) results indicate that incorporating MWCNTs into PVDF caused the formation offl phase. A thermal annealing at 130 ℃ confirmed that the β phase was stable in the nanocomposites. Differential scanning calorimetry(DSC) results indicate that the melting temperature slightly increased while the heat of fusion markedly decreased with increasing MWCNT content. The tensile strength and modulus of PVDF were improved by loading the MWCNTs. The scanning electron microscopy(SEM) observations showed that MWCNTs were uniformly dispersed in the PVDF matrix and an interfacial adhesion between MWCNT and PVDF was achieved, which was responsible for the enhancement in the tensile strength and modulus of PVDF.