The invention discloses a novel coal-fired supercritical carbon dioxide Brayton cycle single-stage division power generation system which comprises a boiler and a supercritical carbon dioxide Brayton cycle power generation system body. The boiler comprises a hearth, a horizontal flue and a tail flue which communicate in sequence. A water cooling wall, a wall type reheater and a screen type superheater are sequentially arranged in the hearth in the smoke flowing direction. A high-temperature reheater is arranged in the horizontal flue. A low-temperature reheater, a secondary air preheater and a primary air preheater are sequentially arranged in the tail flue in the smoke flowing direction. A low-temperature superheater is arranged in the tail flue. The low-temperature reheater and the low-temperature superheater are arranged side by side. According to the system, the exhaust gas temperature of the boiler can be reduced, and the heat efficiency of the boiler and the efficiency of the power generation system body can be improved.