Based on the electrically control characteristics of liquid crystal, the band-gap of an perfect two-dimensional photonic crystal which is composed of triangular lattice circular air holes, the spectrum of liquid crystal 5CB filled photonic crystal fiber for different angles θ which are between the direction of external electric field and x-axis, and the optical field distributions when the wave source wavelength is 2504 nm and different defect modes wavelength are numerically calculated by finite-difference time-domain (FDTD) and perfectly matched layer (PML). The results show as follow: the band-gap of an perfect two-dimensional photonic crystal ranges from 2335 nm to 2438 nm; the defect modes move to short-wave with the increasing of the angle θ, and the maximum value of regulation is 73 nm when the angle θ ranges from 0° to 90°; the light energy will not localize at the fiber core when the wave source wavelength is not within the band-gap limits; the light energy will localize at the fiber core when the wave source wavelength corresponds to different defect modes wavelength, and its distribution is more homogeneous with the increment of the angle θ.