Abstract: In order to generate high birefringence in photonic crystal fiber (PCF), a special structure of PCF was designed, the core area was designed as diamond shape, and the cladding was arranged with hexagonal circular air holes. The transmission characteristics of the optical fiber, such as birefringence, confinement loss, dispersion, nonlinear coefficient and mode field area, were analyzed theoretically. The full-vector finite element method was used to calculate the birefringence as high as 0.0524 at the wavelength of 1.55 µm, and the confinement loss in the x-polarization direction was only 2.49×10⁻⁶ dB/m. The nonlinear coefficient can reach 52.512 W⁻¹·km⁻¹, and the mode field area is 2.4703 µm². In the wavelength range of 0.95 µm ~1.85 µm, the dispersion in the x-polarization direction is (0.775±2.645) ×10⁻¹² ps/(nm·km). This high birefringent photonic crystal fiber has a good application prospect in optical communication, optical sensing and other fields.