Based on the polarization effects and multiple- beam interference effects of optical thin films, a polarization beam splitter (PBS) consisting of multiple TiO2-SiO2 thin film layers is designed, then the hybridintegration scheme within an optical waveguide is proposed and the integration structure is optimized with finite- different time- domain (FDTD) numerical method. The hybrid integration is realized as follows. The multiple TiO2- SiO2 thin film layers are deposited on a substrate made of polymer material, while a slot is fabricated in the polymer waveguide. The thin film element is then inserted in this slot to assemble a compact and hybridly integrated PBS. This hybrid integrated PBS is also characterized experimentally. The results show that, in the C-band (1530 nm to 1565 nm), the device insertion loss is smaller than 2.5 dB, and the polarization splitting ratio is higher than 25 dB. Such a hybridly integrated PBS can be used in present polarization-control optical systems. It also exploits the advantages of the thin film polarization element, thus provides novel schemes and more degrees of freedom, to realize miniaturized and densely integrated PBS.