The invention discloses a power generation system utilizing billet radiant energy and supercritical carbon dioxide cycle, and belongs to the technical field of waste heat power generation. The power generation system comprises a circulating unit and a power generation unit, the circulating unit comprises a high-temperature regenerator, a low-temperature regenerator, a recompressor, a secondary compressor and a primary compressor, and the high-temperature regenerator is connected with the power generation unit through a pipe. A high-temperature side outlet pipe of the high-temperature regenerator is provided with a regulating valve to separate the pipe into two branches for separation and multi-stage compression of a working medium, so that the backheating efficiency can be improved significantly, the multi-stage compression process overcomes the problem that the pressure of a working medium at the turbine outlet and the pressure of a working medium at the compressor inlet are interdependent and parameters cannot be adjusted independently in the supercritical carbon dioxide Brayton cycle is solved, so that the circulation efficiency of the system is improved greatly.