In this paper, a new type PCF with three different air-hole diameters in cladding region is proposed and investigated by using a compact 2-D finite difference frequency domain (FDFD) method with anisotropic perfectly matched layers (PML) absorbing boundary conditions. Through numerical simulation we found that by optimizing the geometrical parameters, our proposed structure with fewer of air-hole rings greatly meets the performance criteria such as ultraflattened dispersion and low confinement loss, which is highly instructive for designing photonic crystal fibers.