Abstract: The running speed and dynamic range of existing correlators cannot meet the requirements of photon correlation spectroscopy. The structures of linear and multi-tau correlator were analyzed in order to overcome this disadvantage. An optimized correlator which included the fast channels by using multi-tau correlator and the slow channels by using linear correlator was proposed based on the advantages of both correlators. Therefore, a fast photon correlator with high dynamic range was designed by the optimized structure. Experimental data show that the sampling time of the fast photon correlator can be set to 10ns, the maximal dynamic range is 1.11012, and the baseline error is 0.095% by using modified normalization method.