Abstract: Radiation effect of color CMOS digital image sensors was studied by accumulative radiation and single dose radiation at different γ-ray doses. The quality of the picture captured under natural lighting is very poor only at 1.2 kGy for accumulative radiation, but at 1.8 kGy for single dose radiation, showing that the radiation-induced degradation of the device performance for the sensor with accumulative γ-ray doses is much more severe than those with single dose due to like power-on mode.