The dispersion properties of photonic crystal fiber (PCF) was analyzed by an effective refractive model, and the eigenvalue equation of the fundamental space filling mode in infinite air silica micro structure was presented. The analysis results show that PCF has unusual dispersion property, which can support single mode transmission in a very large wavelength range and have anomalous dispersion under singe mode operation. Zero dispersion wavelength can be shifted by adjusting the structure parameters of PCF. Finally, PCF with large air holes and its applications in dispersion compensation were also discussed.