Abstract: Photonic crystal fiber is a highlight of the modern science research.However,in most papers,only qualitative analysis have been carried out theoretically,and there are few practical quantitative calculation.The group velocity-dispersion of photonic crystal fiber(PCF) is studied with plane wave method(PWM) and supercell method.The effective index of the fundamental filling mode and V value are obtained.With obtained effective index,dispersion is calculated using spline interpolation,according to different relative hole size f and different pitch a.Simulation results prove the monochromic property and controlled dispersion property of a photonic crystal fiber.