We demonstrate a high quality and high counting rate source of entangled photon pairs through four-wave-mixing (FWM) by pumping a 40m dispersion-flattened photonic crystal fiber (PCF). This pair of photons, which are called signal/idle wave, is found at 1545 nm and 1555 nm, respectively. The coincidence and accidental coincidence ratio (C/A) can reach to 8, with the coincidence rate of 1.43 kHz.. The computer results have tallied in general with the experiment. Such a system can be used as the source of quantum key distribution system with a bit error rate less than 6%.