Poly(vinylidene fluoride) (PVDF) was blended with cetyltrimethylammonium bromide (CTAB)-modified illite through a solvent-casting method. The effects of the content of modified illite and temperature on gamma-phase PVDF crystallization were studied in detail. Unmodified illite does not affect the crystallization of PVDF. By contrast, modified illite can effectively boost the nucleation of the gamma-phase due to the electrostatic interaction between PVDF and modified illite. For PVDF with low contents of modified illite, for example, 0.5 wt %, the ability to obtain the gamma-phase is enhanced at 155 degrees C compared with neat PVDF. Increasing the crystallization temperature or the content of modified illite facilitates to form more gamma-phase. Blending of 2.0% modified illite generates a pure gamma-phase regardless of crystallization temperature. The technique to prepare pure gamma-phase PVDF materials has a huge potential application in the fabrication of cheap pyro- or piezoelectric devices.