A polarization splitter based on dual-core photonic crystal fiber (PCF) with short-length and ultra-high extinction ratio is proposed, and the coupling property of the dual-core photonic crystal fiber and the performance of the splitter are studied numerically based on full vector finite element method (FEM). It is found that the coupling length of the dual-core PCF can be reduced obviously by enlarging the ellipticity of the hole between the two cores and adjusting the doped index properly, a polarization splitter based on the proposed dual-core PCF with a length of 0.58 mm is achieved that can separate the x polarized light and y polarization lights and the extinction ratio of the splitter can reach 82.33 dB at the wavelength of 1.55 μm. Meanwhile, the bandwidth of extinction ratio more than 20 dB and 10 dB can be as wide as 70 nm and 110 nm, respectively, which covers the C+L wavelength bands. This proposed splitter provides a new structure for designing a splitter with short length, wide bandwidth and high extinction ratio.