In order to achieve the effect of pressure sensitization of optical fiber sensor, a photonic crystal fiber structure with high birefringence was designed. The effective refractive index of photonic crystal fiber was calculated by the finite element method when it was applied different stress. Based on the pressure-sensitive characteristics of photonic crystal fiber, the mode of photonic crystal fiber was analyzed. An air hole in the structure was selected and filled with the liquid of specific refractive index. A new pressure sensor was formed by above structures. The pressure sensitivity of the structure was simulated by COMSOL. The simulation results show that the polarization phase sensitivity of photonic crystal fiber sensor increases from 72rad/(MPa·m) to 128rad/(MPa·m). The sensitivity is improved by 77.7% significantly, which contributes to enhance the properties of the sensor.