Abstract: The change in optical properties and the damage mechanism of ZnO/silicone white paint caused by low energy protons were investigated in terms of ground-based simulation testing. The results show that the solar absorptance ratio increases with the increase of irradiation fluence of proton as well as the proton energy. Under proton exposure, the degradation in optical properties of ZnO/silicone white paint mainly occurs in the visible radiation region of the solar spectrum. The damage mechanism was studied by Fourier transform infrared spectrum. The amount of free oxygen increases under proton exposure. Free oxygen would oxidate the radicals in the silicone binder and form active hydroxide radical (—OH), which could accelerate the break of Si—O—Si bond. Meanwhile, the no-bonding lone-pair