A real time optical correlator with high discrimination is suggested in this paper. In this correlator, a liquid crystal light valve (LCLV) is used as real time input and image preprocessing device. In recording hologram, a piece of photorefractive crystal (Fe∶LiNbO 3) is used as holograhic recording material and a convergent spherical wave as reference light wave. the correlator is characterized by high discrimination, real time and flexible processing, and compact constructure.