A new compact polarization beam splitter based on the self-collimation effect of two-dimensional photonic crystals and photonic band gap characteristics is designed in this paper. The size of the entire device is 9 μm×9 μm. The self-collimation effect of photonic crystals is used to realize TE polarized light and TM polarization. The self-collimation propagation of light in the self-collimation structure utilizes the photonic band gap characteristic to realize the orthogonal separation of TE polarization and TM polarization. When the number of air holes of the inserted polarization beam splitting structure is 5， the transmittance of TE polarized light at 1 550 nm is 95.4%， the corresponding polarization extinction ratio is 23 dB， and the transmittance of TM polarized light is 88.5%， which corresponds to the polarization extinction ratio is 37 dB. For TE and TM polarized light covering a 100 nm bandwidth， the TE polarization extinction ratio and TM polarization extinction ratio are higher than 18 dB and 30 dB， respectively. Compared with the previous polarization beam splitter， the structure is simpler， the size is smaller， and the polarization extinction ratio is higher， which better meets the needs of modern optical communications and optical integrateion systems.