To describe the photoelectron rise and decay process of AgCl microcrystals doped with ［Fe(CN)6］4-, a kinetics model composed of three in trinsic centres and a shallow electron traps(SETs)is set up, and further more, a set of differential equations is deduced. By solving the differential equations, photoelectron decay curve and photoelectron lifetime that is in accord with the transient microwave photoconductivity experimental data are obtained. Adjusting related simulation parameters, the SET depths and capture cross sections at room temperature for ［Fe(CN)6］4- are obtained and they are 0.115eV and 2 .136×10-17cm2, respectively.