Pseudo-thermal light is a regular sou rce for correlated imaging.Copared to entangled bi-photon source,it can be easi ly obtained and put to use in experiment.Pseudo-thermal light and entangled bi -photon are similar in some particular ways,especially in photon statistics whi ch is the key to correlated calculation.A quantum state is classical if it is a coherent state or a classically-random mixuture of coherent states.Thus the zer o-mean Gaussian state can be used to describe the phase-insensitive coherenece propagation of pseudo-thermal light.Based on this model,semi-classical photo -detection therory of pseudo-thermal ight can be build,correlation function of signal path and reference path can be derived.So that the resolution and contra st of ghost image and view of GI system can be analyzed.