The unsatisfactory aspects of currently applied technologies for combustion of pulverized coal are reviewed and the concept of a movable heat-insulating refractory device (MHRD) is proposed to improve the overall performance of coal-fired boilers. The structure and working principles of the device, which is installed on a furnace waterwall and can move up and down during operation so as to maintain a proper high,flue gas temperature in the space near the burner in case of low load or low rank of coal, are detailed and relevant calculations and experimental results are introduced. The results show that a MHRD based on a multilayer of microporous ceramic board can work safely at high temperature with,air cooling and has great potential for improving overall performance of pulverised-coal-fired boilers in terms of combustion stability and efficiency, steam temperature characteristics and adaptability to load and coal fluctuation.