Dispersion and polarization properties of near_rectangle core photoric crystal fibers (PCFs) were analyzed with a full vector model. The numerical results show that the modal birefringence of near_rectangle core PCF is at least one order of magnitude higher than the conventional elliptical polarization_maintaining fibers (PMFs). In order to obtain higher birefringence, an efficient way is to increase the relative hole diameter. Zero walk_off point occurs at the longer wavelength than that of convention elliptical PMF. With increasing hole pitch, the walk_off curve and zero walkoff point would shift towards the longer wavelength region. The corresponding wavelength of zero walkoff point is in proportion to the size of the hole pitch. The occurrence of zero walkoff point can efficiently restrain the first_order polarization mode dispersion. Through choosing the suitable structural parameter of near_rectangle core PCF, we can get the more flexible dispersion properties. The approximate 400nm ultra_flatten dispersion was gotten near the wavelength 155μm for a nearrectangle core PCF with Λ=2μm and d/Λ=03 This fiber has a number of potential applications in polarization control, dispersion control and management.