The temporal behavior of free photoelectrons and shallow-trapped electrons in the T grains AgBrI emulsion was detected with the microwave absorption and dielectric spectrum detection technique. The results indicate that the effect of sensitization center on the photoelectron decay differs in different time ranges of the first-order decay curves, and that the electron trap effects of sulfur+gold sensitization center change from shallow trap to deep trap with increasing sensitization density. The optimal sensitization density of sulfur+gold was obtained on the basis of the relationship between the sensitization density and the decay time.