Abstract: In the background of "carbon peak and "carbon neutrality", coal-fired power generation is the most economical adjustment power source for the large-scale consumption of renewable energy. Circulating fluidized bed (CFB) combustion technology plays an important role in deep and flexible peak shaving of coal-fired power generation due to its unique advantages such as strong combustion stability at low load, low cost of pollutant control and wide range of load regulation. However, its unique combustion mode leads to slow load change rate, which cannot meet the adjustment demand of large-scale integration of renewable energy into the grid in the future. Combined with the combustion principle and application scenarios of a CFB boiler, the key factors that restrict the load change rate of the CFB boiler are analyzed in depth, including the flow inertia of circulating ash, the reaction inertia of fuel, the heat transfer inertia of bed material and abrasion resistant refractory materials, and the emission of pollutants. Besides, the feasible regulation technology of rapid variable load in circulating fluidized bed is discussed and analyzed, which provides some reference for the industrial application of the depth and rapid regulation technology of coal-burning CFB.