Poly(vinylidene fluoride) (PVDF) has been widely used as transducers, actuators,and sensors due to its exceptional electroactive properties among polymer materials and the electroactive properties of PVDF heavily depend on its polymorphs. The effects of cetyl trimethyl ammonium bromide (CTAB) on the crystallization behavior of PVDF during isothermal crystallization and annealing process were studied, and the results showed that the polar phases (beta, gamma) were induced by CTAB when PVDF was isothermally crystallized at 145-160 A degrees C. Increasing the isothermal crystallization temperature resulted in an increased gamma-phase formation with a concomitant decrease of alpha and beta phases. A 100 % gamma-phase formation occurred when the sample isothermally crystallized at 155 and 160 A degrees C. The crystalline phase transition of the sample annealed at 160 A degrees C for various time revealed that CTAB induced the transformation from alpha to gamma' phase and a higher concentration of CTAB resulted in shorter transformation time, as well as higher transformation degree.