Abstract: Monte Carlo computer simulation technique was used for studying the mechanism of latent image formation in cubic crystals of silver bromide. Based on some significant results from the researches on latent image,certain fundamental assumptions were made in this model as follows: 1) before the ionic step starts the electrons released by photons rapidly reach an equilibrium between electrons in conductance band and those in shallow traps,as which interstitial silver ions may act besides kink sites and dislocation jogs; 2) formations of Ag,Ag₂,and Ag₃ (nucleation) are inefficient,whereas the growth after the formation of Ag₄⁺ is efficient; 3) positive holes produced by photons will have an evolution from holes to Br2 through V-Centers and bromine atoms,and during the evolution recombination and regression may take place. The estimation of parameters for simulation is based on some physical measurements,such as by microwave technique and dielectric loss etc. The results from simulation quantitatively show the productions and the changes of various species,such as reactants,intermediates,and products,and also show a consistency with some of macroscopic experimental results,response curves and reciprocity curves as for instance.