The design of a polarization beam splitter(PBS) is presented according to different band gaps with different photonic crystals. The splitting properties of the PBS are numerically simulated and analyzed by using the finite-difference time-domain method and the plane wave expansion method. It is shown that a highly efficient splitting for TE mode and TM mode can be achieved. The transmission probability is above 92% for both TE mode and TM mode while the incident wave is Gaussian and the wavelength range is 1.5～1.58 μm. Especially the transmission probability can reach 95.5% for TE mode and 99% for TM mode the 1.55 μm Gaussian incidence. Meanwhile, its size is only 10 μm×11.5 μm. The PBS makes a promising candidate in the future integrated optical circuit.