A kind of dual-core highly birefringent photonic crystal fibers (PCF) is proposed. The model introduces the asymmetrical structure through replacing the innermost eight air holes with four elliptic air holes. The mode birefringence, coupling length and dispersion characteristics are studied by changing the hole size between the two cores, ellipticity of elliptic air holes and hole pitch. The results show that the mode birefringence is up to 10-2, the coupling length is as short as 0.1367 mm, and the dispersion is very flat from 1.0 μm to 1.6 μm.