Abstract: Nowadays, CMOS image sensors are more and more used in a wide variety of applications, especially in satellite systems, where they are exposed to space radiation environment. In-orbit sensors suffer from radiation induced dark-current degradation that the dark-current mean value and non-uniformity increase, which results in the signal-to-noise-ratio decrease affecting the image quality. Based on the principle of radiation effects on semiconductor devices, this paper analyzes the ionizing and displacement damage effects in CMOS image sensors due to γ-rays and protons radiation, and proposes a method for dark-current distribution modeling in the mixed radiation environment. Simulation results proves that the proposed method is well adapted to predict the dark-current distributions for a device which is exposed to both rays and protons radiation at the same time.