The existing status and main characters of thin- film polarizing beam splitter (PBS) are pre- sented and demonstrated. Frustrated total internal reflection and thin film interference are simultaneously employed to allow S- polarized light to be transmitted and P- polarized light to be reflected over a wide range of wavelengths and angles of incidence. The PBS is operated at angles greater than the critical an- gle. The basic design principle is emphatically analyzed. The design of PBS is applied in projection sys- tem. The spectral wavelength region of the design is 420～680 nm,with the range of incident angle of ± 10°in air.The extinction ratios for the reflected and transmitted beams are over 1000.