An ultra broadband single-polarization single-mode (SPSM) photonic crystal fibre (PCF) is proposed and analysed by using the plane-wave expansion method and the beam propagation method. Numerical results demonstrate that the SPSM wavelength region nearly at 580nm in width from 1.46μm to 2.04μm is obtained in this PCF. The start wavelength of the SPSM region is close to the hole pitch, and the width of the SPSM region increases with the increasing hole pitch. Effects of dopant concentration on SPSM properties are investigated. The confinement loss decreases and the width of SPSM region widens slightly with the increasing dopant concentration. These results offer a new possibility of fabricating active doped SPSM PCFs with high performance that is crucial for improving the performance of linearly polarized fibre lasers.