Abstract: The insufficient combustion stability of boilers at low loads is an important reason that limits the flexible operation of coal-fired power units. Increasing the initial temperature of the pulverized coal stream can directly reduce the ignition heat of the pulverized coal stream, which can improve the combustion stability of boilers at low loads. The simulation calculations of a 600 MW coal-fired power unit show that the minimum stable combustion load of the boiler can reduce by about 7% while the initial temperature of pulverized coal stream increases by 100℃. Subjected to the requirements of the safe operation of the mill, the initial temperature of the pulverized coal stream is generally low for the coal-fired power unit using the direct blowing pulverizing system. The existing methods for increasing the temperature of pulverized coal stream include hot air mixing, furnace flue gas mixing, and steam heating. With hot air mixing, the temperature of the pulverized coal stream can be increased to about 200 ℃, but the concentration of pulverized coal decreases significantly, and the ignition heat of the pulverized coal stream increases. The shade separation of pulverized coal stream is necessary for combustion stability of boilers. The NO_x concentration increases with hot air mixing. With furnace flue gas mixing, the temperature of the pulverized coal stream can be increased to 200–300 ℃ and the NO_x concentration decreases. But the concentrations of pulverized coal and O₂ decrease significantly, the cost of high-temperature furnace flue fans is high and the maintenance of high-temperature furnace flue fans is difficult. With steam heating, the temperature of pulverized coal stream increases and the energy efficiency increases. However, the heating effect of low-pressure steam is poor, and it is difficult to manage pressure vessels when high-pressure steam is used. The existing pulverized coal stream heating methods have certain deficiencies and have not been widely used. A novel system for pulverized coal stream heating is proposed, turbine extraction steam is used as the heat source, thermal oil is used as the intermediate heat exchange medium, plate-fin heaters on the pipe are used to heat the pulverized coal stream. By practical application on two coal-fired power units, it is proved that the system can increase the temperature of pulverized coal stream by 60-80 ℃ which increases from 80 ℃ to 140–160 ℃.