The detailed operational performance, gas-solid hydrodynamics, and combustion characteristics in a 600 MW coal-fired CFB boiler with a novel annular furnace, which was designed to meet the significant increase in heating surfaces for supercritical carbon dioxide (S-CO2) cycles, were studied in this article. In multiphase particle-in-cell (MP-PIC) simulations, the flow pattern and pressure drop were explored in a wide range of operating gas velocities to determine the suitable operation interval. Within a fast-fluidized bed, affected by the increasing fluidization velocity, the voidage and gas-solid velocity obviously increased, indicating good flexibility and adjustability of the annular CFB for varying operating conditions. At the most representative operating velocity, the annular S-CO2 CFB showed relatively more satisfactory dynamic and combustion characteristics compared with conventional steam CFBs, including a uniform temperature distribution, larger heat flux, and lower pollution emissions, which indicated good heat transfer characteristics of S-CO2 heating surfaces and higher combustion efficiency.