The invention relates to a totally closed Breton cycle heat-power conversion device. The totally closed Breton cycle heat-power conversion device comprises a rotor, wherein an electric generator rotor, a low-pressure compressor rotor, a turbine rotor and a high-pressure compressor rotor are sequentially and vertically arranged on the rotor from top to bottom; the electric generator rotor is arranged in an upper air cylinder, and the low-pressure compressor rotor, the turbine rotor and the high-pressure compressor rotor are arranged in an air cylinder, and the air cylinders and the upper air cylinder are connected through static seal and are integrated, so that a totally closed structure is formed; through reasonable layout of medium gas inlets and outlets of a low-pressure compressor, a turbine and a high-pressure compressor, the leakage of high-temperature media of the turbine to a high-pressure compressor, the low-pressure compressor, a bearing, an electric generator and the like canbe avoided, and the structure is compact; meanwhile, it can be ensured that the temperature of the air cylinder where the bearing is located is low, extra cooling measures are not needed, the problemthat the temperature and the pressure of the bearing are not stable can be solved, safe and stable running can be achieved, the pressure difference of the two sides of the shaft seal between the aircylinders can be small, the leakage amount is small, and the unit efficiency is improved.