A dynamic model and the relevant nonlinear coupling equations describing dynamic responses of photoconductive(PC) semiconductor detectors were established based on photocarrier transport and the temperature rising in detectors under high power laser irradiation.The dynamic responses of PC semiconductor detectors to laser irradiation were obtained through numerical calculation of the equations.The results of numerical simulation are identical with experimental results.The model can be applied to any power light irradiation.Identical results between this model and traditional model are achieved when low power laser irradiate.The model can describe saturation effect of PC simiconductor detectors under high power laser irradiation.