An efficient and accurate method was developed for modeling photonic crystal fibers(PCF).The transverse refractive index profiles were decomposed by cosine functions and a 2-D step function,and the modal field was expanded by Hermite-Gussian functions.The propagation constant and the modal field distribution of the PCF can be calculated by recasting the Maxwell equations into eigenvalue system.With this method,the propagation properties including dispersion properties,polarization properties and effective area can be investigated.