Abstract: In order to study the operating characteristics of the oxy-combustion unit under different load change rates, a 35 MW_th oxy-combustion boiler island dynamic simulation model was established, and a closed-loop control unit for the flue gas side and water side was built. Firstly, the system response characteristics were verified after a 4% step change in fuel quantity. On this basis, the variation of the process parameters under the regulation of the control system were simulated at the load change rate of 2%/min and 5%/min. Results show that the simulation results are in good agreement with the actual operation data, and the control process of this control system is stable and converges quickly. The system is more stable at 2%/min load change rate. To obtain more reasonable output parameters, the load change rate during system operation should be minimized as much as possible