In this article, Hansen solubility parameters (HSP) have been used to evaluate the dispersion state and interfacial strain transfer ability of purified, nitric acid-functionalized and octadecylamine-functionalized single-walled carbon nanotubes (SWNTs) as the reinforcing materials in a poly(vinylidene fluoride) (PVDF) matrix. Composites were prepared by solution blending of PVDF and SWNTs and injection molding. The observations of the dispersion were obtained by dynamic light scattering and light optical microscopy and compared with the HSP results. The interfacial strain transfer between the polymer matrix and the carbon nanotubes in SWNTs/PVDF composite was studied by measuring the shift of the Raman two-dimensional peak position under tension. It was found that the strain transfer is affected by the degree of homogeneity of the fillers in the composites, the carbon nanotube bundle size and the affinities between two materials.