We report on the preparation and the characterization of TiO2 nanoparticles incorporated with nylon-6 composite nanofibers by using electrospinning technique. Two different composite nanofiber mats with TiO2 nanoparticles sizes of 20 and 300 nm were prepared. The resultant nanofibers exhibited good incorporation of TiO2 nanoparticles. The doping of TiO2 nanoparticles into the nylon-6 nanofibers was confirmed by using scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM), X-ray diffraction (XRD) and energy dispersive X-ray (EDX) spectroscopy. The measurement of the electrical conductivity of the TiO2 nanoparticles incorporated with nylon-6 nanofibers were carried out. Current-voltage (I-V) characteristics revealed that the current was enhanced for the sample with 300 nm TiO2 nanoparticles compared to that with 20-nm TiO2 nanoparticles.