A new one-dimensional ternary photonic crystal containing electro-optical material LiNbO3 is proposed. Based on transmit matrix method, the photonic band-gap varied with external field is simulated and analyzed in near infrared region. The simulation results show that the defect mode is found to merge inside photonic band-gap with the impact of external field, and the peak wavelength of defect mode can be tuned by adjusting the external field. Moreover, the angle-dependent peak position of defect mode is also examined, which opens a promising way to design tunable wavelength filters in near infrared region.