The dispersion property of a 0.6 m-long photonic crystal fiber (PCF) is deduced by characterizing its phase matching condition of spontaneous four wave mixing (SFWM) through pumping the PCF with a pulse train having a pulse duration of 1.6 ps. When the central wavelength of the pump is varied from 1037 to 1047 nm with a step of 1 nm, the spectra of signal and idler photons via SFWM are measured by using tunable filters and single-photon detectors. Using the step effective index model, and fitting the 11 sets of experimentally obtained data of SFWM phase matching, the effective core radius and air fraction of the PCF are found to be 0.949 μm and 29.52%, respectively. Accordingly, the dispersion property and the SFWM phase matching curve of the PCF in the whole spectral range are then calculated. Experimental results show that the predicted wavelengths of phase matching agree with the measured values, and the differences are less than 0.1%.