In this paper the authors present a modified octagonal photonic crystal fiber (M-OPCF) with nearly zero flattened dispersion while possessing extremely low confinement losses and high birefringence characteristics within a wide bandwidth. The finite difference method (FDM) with anisotropic perfectly matched boundary layers (PMLs) is used to investigate these transmission properties. By using a modified OPCF, nearly zero flattened dispersion of about OtO.75 ps/(nm-km), low confinement loss of less than 1006 dB/km and high birefringence is demonstrated over the bandwidth of 310 nm. And then analyze the sensitivity of the chromatic dispersion to small variations from the optimum value of specific structural parameters, and estimate the fabrication accuracy required for the reliable fabrication. The low flattened dispersion feature, as well as the low confinement loss and high birefringence characteristics are the main advantages of the proposed PCF module, predicting its potentiality in chromatic dispersion controlling, polarization maintaining and in WDM network applications.