The present application discloses a method and an apparatus for solar power generation through gas volumetric heat absorption based on characteristic absorption spectrum. A radiation energy conversion device absorbs concentrated solar radiation and converts radiation energy into thermal energy; the thermal energy is transferred to the other side of the radiation energy conversion device and then is converted into radiation energy; and the energy is transferred in a receiver cavity. The working gas from the outlet of a recuperator flows into the receiver cavity and absorbs the radiation energy. The heated working gas with high temperature flows into a turbine, doing shaft work through expansion. The expanded working gas flows through the recuperator to exchange heat. The working gas flows into a cooler, a compressor and the recuperator in sequence, and then flows into a receiver cavity to be heated volumetrically, completing a thermal power cycle.