Abstract: Responsivity is an important factor for reflecting the performance of photoelectric detector and could be altered if the detector is laser-induced damaged. A system for monitoring real-time responsivity of the detector was developed. A PIN detector was irradiated by Nd∶YAG laser with energy increasing gradually, the relationship between the responsivity of detector and the power density of incident laser was obtained. The detector remained its performance when irradiated by laser with the power density of Nd: YAG laser less than 7.6105W/cm2, the responsivity of the detector was constant for 532nm reference light. When the power density of laser was more than 1.27106W/cm2, with increasing incident laser power density, the responsivity of the detector was reduced slowly. When the power density of laser was more than 1.27106W/cm2, the responsivity of the detector was reduced sharply after being irradiated. The reason for the fall of responsivity was analyzed. The conclusion was confirmed by scanning electron microscope photographs (SEM).