The disturbance and damages of TEA-CO2 laser to HgCdTe imaging sensor are researched experimentally and theoretically. The saturation of pixels of the HgCdTe detector just appears inside the facula when the energy density on it is less than 255 mJ/cm2. Pixels are damaged when the energy density is 425.8 mJ/cm2, and a dispersed spot and a dark ring are observed. By the simulation of the HgCdTe detector under CO2 laser irradiation, the temperature distribution of the detector is calculated. The relationship among temperature-rise, carrier density and mobility of the detector is discussed. The dispersed spot occurs because of free carriers excited by heat diffuse under carrier density grades. The dark ring appears because of both of the mobility changing and carrier density diffusing. Hg atoms separate out from the detector due to their high temperatures, resulting in the pixels damage.