To numerically investigate the adjustment of the fundamental mode characteristics of PBG-PCF with six-fold rotation symmetry（C6v） by the central air fiber core radius

full vector plane wave and multipole method are used to calculate the bandgap structures of this kind of fibers and the effective refractive rate of any possible fundamental modes with different central air fiber core radiuses

from which the fundamental mode dispersion

nonlinearity and confinement loss are analyzed.The numerical results demonstrate that the greater the central air fiber core radius

the greater the dispersion

and the dispersions at high wavelengths oscillate and vary near zero dispersion with the incident wavelength

that the nonlinear coefficient at a specific wavelength increases with the increase of the central air fiber core radius

and that the fundamental mode confinement loss as a whole decreases with the increase of the incident wavelength

displaying oscillating behavior at certain air core radiuses.