Currently, most polarization beam splitters are large in volume, and can hardly be used in optical integrated circuits. However, micro devices including the polarization beam splitter can be manufactured on the basis of photonic crystals. Up to now, there are two kinds of polarization beam splitter based on photonic crystals, one of which utilizes a photonic crystal with an S-polarization-wave bandgap and a P-polarization-wave transmission band, or with a P-polarization-wave bandgap and an S-polarization-wave transmission band to realize the polarization splitting of the wave. This kind of polarization beam splitter can only be used as a separate photonic crystal device in conventional optical waveguides, and is difficult to be integrated into other photonic crystal devices, since the transmittance and degree of polarization thereof are poor. The other kind is based on coupled waveguides with different relative coupling lengths for coupling light waves in different polarization states into different waveguides by means of long-distance coupling between waveguides, utilizing the method of periodic coupling and odd-even state alternation between the waveguides. The polarization beam splitters obtained by the two methods mentioned above, still have a relative large volume and a narrow range of operation wavelength, so they are not conducive to practical applications.