Abstract: Coal-fired power generation units based on circulating fluidized bed (CFB) combustion technology can achieve long-period near-zero load (banked-fire) operation with rapid start and stop capabilities, thereby enabling full-load regulation. Experimental results on a 300 MW subcritical CFB boiler demonstrate that the unit's power can rapidly drop to 1 MW at a rate of 10.4% Pe/min and then maintain long-term stable operation at an ultra-low load ratio of 1%, with a total hot standby duration exceeding 110 minutes. After finishing the banked-fire operation, the unit can restart at a rate of 3.5% Pe/min. During this period, the average bed temperature decreases from 800 ℃ to 553 ℃ at a rate of 2.2 ℃/min; the main steam temperature and pressure drop by 165 ℃ and 1.7 MPa, respectively; the lateral temperature deviation of each heating surface is basically within 10 ℃; and the turbine and generator operate smoothly with all parameters within safe limits. During the load lift phase, the instantaneous CO concentration in the flue gas rises sharply above 1%, but there is no risk of explosion. The hourly average emissions of dust, sulfur dioxide, and nitrogen oxide pollutants throughout the peak regulation process meet ultra-low emission standards. This study provides a more competitive direction for further enhancing the flexibility of coal-fired power units, which is of great significance for accommodating a high proportion of renewable energy sources, as well as for ensuring the reliable and stable operation of new electric power systems.