Abstract: To study the performance of an S-CO₂ recompression Brayton cycle, a mash model was established, based on which, the effects of following key parameters on the cycle efficiency were analyzed, such as the inlet temperature and pressure of both the main compressor and turbine, the efficiency of corresponding equipment, and so on, while the influencing mechanism was explored and the optimal working point was designed. Results show that the cycle efficiency increases monotonically with rising inlet temperature and pressure of the turbine, and with reducing inlet temperature and pressure of the main compressor. There exists an optimal inlet pressure of the main compressor that makes the cycle efficiency reach the maximum. The cycle efficiency is related to the efficiency of corresponding equipment in the cycle loop, among which, the turbine isentropic efficiency and the high-temperature recuperator efficiency affect the most.