A novel dual-core photonic crystal fiber (PCF) for broadband polarization-insensitive coupler with elliptical central hole is proposed. The impacts of its structural parameters on coupling characteristics are investigated in detail using full-vector finite element method. Optimizing fiber structure parameters, dual-core PCF is obtained and meets the application requirements of easy to fabricate, free to splice and low splice loss. Then an improved dual-core PCF is proposed for reducing the difficulty of fabrication. The coupler based on this fiber is obtained with the coupling ratio stabilized at (50±1)% and the coupling ratio difference between x polarization and y polarization less than 0.2% in wavelength range of 1.26~1.625 μm.