Abstract: The supercritical CO₂ Brayton cycle power generation system combined with high temperature particle heat storage system is considered as one of the important and potential technical directions of the new generation concentrating solar power units. The deep study on the dynamic characteristics of supercritical CO₂ Brayton cycle is an important basis for the efficient and flexible design and operation of the new generation concentrating solar power units. In this paper, a dynamic simulation model is established, tailored for the supercritical CO₂ Brayton cycle unit coupled with a particle heat exchanger, in Xi'an Thermal Power Research Institute Co., Ltd. In the unit, the turbine and compressor are arranged in separate shafts. Then, the dynamic simulation calculation is carried out. The results demonstrate that the system can reach a new stable state faster in the condition of particle/water mass flow rate step change than that in the condition of particle/water inlet temperature step change. The influence of compressor speed disturbance on mass flow rate is rapid and obvious. Compressor speed regulation can be used as an important means of the mass flow rate control. The optimal rotational speed of the turbine is different under different mass flow rates. When the turbine rotational speed changes closer to the optimal rotational speed, the cycle net efficiency increases. When it goes far away, the cycle net efficiency decreases.