The microwave absorption dielectric-spectrum technique was used to study the decay kinetics of photoelectrons in sulfur-sensitized silver halide crystals. The time-resolution spectrum of free electrons and shallow-trapped electrons generated in sulfur-sensitized AgBrI crystals has been obtained. The relationship of the trapping effect of sensitization centers Ag2S and sensitization time or temperature in emulsions has been discussed. With the increase in the sensitization time and temperature, the trap effect of sulfur sensitization centers varies from hole trap to shallow electron trap, and deep electron trap.