An irradiation experiment for an image-intensified sensor (Intensified Complemetary Metal-oxide Semiconductor,ICMOS ) was performed with a 60Co-γ ray source to evaluate its weak-light-detecting ability under the total dose irradiation. When the total dose of irradiation reached the predetermined point, the change of photoelectric response capability of the sensor was measured quantitatively by an off line method. The experiment results show that as the total dose of irradiation increases, the photoelectric response capability decreases rapidly. When the total dose of irradiation reaches 60 krad(Si), the photoelectric response capability is reduced to 6%. The causes of decline of the photoelectric response capability were analyzed according to the components of the image-intensified sensor and empirical equations of the decline of the photoelectric response capability were also derived. The experiments demonstrate that the decline of the photoelectric response capability is compensated by improving the voltage gain of the image-intensified sensor. When the total dose of irradiation reaches 25 krad(Si), the photoelectric response capability still maintains 100% by improving the voltage gain of the image-intensified sensor of 0.23 V meanwhile maintaining a good weak-light-detecting ability. These findings show that the image-intensified sensor is able to withstand 25 krad(Si) of the total dose irradiation.