An ultra-high birefringence photonic crystal fiber was designed,which is composed of an elliptical all-solid hole doped with 80PbO·20Ga2O3 in the core and a cladding with periodic hexagonal-lattice air holes.The performance of the modal birefringence and the contribution of different factors were investigated by the full-vector finite-element-method.Numerical results indicate that the modal birefringence has a magnitude of order of 10-1 in the range of wavelength from 910 nm to 1 931 nm.At the wavelength of 1 550 nm,we acquired an extremely high birefringence of 1.256×10-1 and the small effective areas of both orthogonal polarizations (<0.7 μm2).The design of the fiber will be highly meaningful for the development of interferential fiber optic sensors,nonlinear optic and polarization-preserving devices.