The invention discloses a gas endothermal solar power generation method and device based on characteristic absorption spectra. One side of a light energy conversion device absorbs and focuses sunlight and converts the sunlight into heat energy. The heat energy is transmitted to the other side of the light energy conversion device and converted into radiation energy adjacent to characteristic absorption peaks of gaseous working media and the radiation energy is radiated into a heat absorption cavity for heat exchange. Gaseous working media at an outlet of a regenerator enter the heat absorption cavity and three-dimensionally absorb the radiation energy, and the temperature rises rapidly. The heated high-temperature working media enter a turbine to expand and do work. The expanded working media flow through the regenerator to conduct heat exchange. After the temperature decreases, the working media enter a cooler, a compressor and the regenerator in sequence. The working media at the outlet of the regenerator enter the heat absorption cavity again to be heated three-dimensionally, and a heat power conversion cycle is completed. According to the gas endothermal solar power generation method and device based on characteristic absorption spectra, the light energy conversion device is adopted to convert solar energy into the radiation energy adjacent to the characteristic absorption peaks of the gaseous working media, the working media directly and three-dimensionally absorb the radiation energy, and the heat absorption surface area is substantially reduced. A heat absorber is simple in structure, high in efficiency and low in cost.