Abstract: The waveguide polarizer is a key component of an on-chip integrated coherent optical system, and it has attracted much interest to design a waveguide polarizer with an ultrahigh extinction ratio, low excess loss and compact size in photonic integrated circuits. A tilted Bragg grating-based polarizer on a silicon-on-insulator platform was proposed and designed by one-dimensional photonic crystal band gap theory. The energy band structure distribution for the TE and the TM modes were calculated using the energy band theory of one-dimensional photonic crystals, and the overlap gap between the forbidden band of theTE mode and the transmission band of the TM mode were used to determine the grating structure parameters. As a result, the TM mode light could pass through the Bragg grating waveguide with a low excess loss, while the TE mode shows almost complete reflection, introducing an extremely high polarization extinction ratio. The 3D FDTD simulation results suggest that a 16 μm titled Bragg grating-based waveguide polarizer could achieve an ultrahigh extinction ratio of more than 37 dB at the central wavelength of 1550 nm over a broad bandwidth of 70 nm, and the excess loss of the device is less than 0.64 dB. With an increasing length of waveguide to 25 μm, the extinction ratio could further reach up to 46 dB. The effects of the tilt angle and etching deviation on the performance of the polarizer were also studied, and the results show that the designed structure has a good fabrication tolerance. In addition, the polarizer only needs one-step etching with a simple fabrication process.