A novel photonic crystal fiber that maintains single polarization at a relatively wide wavelength range is presented and analyzed with a full-vectorial compact-two-dimensional finite-difference method. When the space of hole to hole is 2.3 μm, the diameter of the larger holes in the first ring is 2.4 μm, the diameter of the smaller air holes in the first ring is 1.4 μm, and the diameter of other air holes is 0.6 μm, this single polarization fiber (SPF) maintains a high mode birefringence at wavelength range of 1.02～2.0 μm. When the diameter of the larger air holes is 2.8 μm, and the diameter of the smaller air holes is 1.4 μm, only one polarization mode can be guided in the range of 1.35～2.0 μm and the modal birefringence at the wavelength 1.31 μm can reach 3.5×10-3.