Ignition difficulty and poor combustion efficiency are the disadvantages of micron-sized aluminum powder in application. To improve the ignition and combustion characteristics of micron-sized aluminum powder in water vapor, a homemade pipe furnace experimental platform was established to study the effects of potassium fluoride (KF) on ignition and combustion characteristics of 30 ?m aluminum powder in water vapor at 1000℃ in this work. The high-speed photographic system was used to record the ignition and combustion process of various samples. The product components, product morphology, and combustion efficiency were analyzed by X-ray diffraction, scanning electron microscopy and chemical analysis method, respectively. The results showed that the potassium fluoride addition into 30 ?m aluminum powder significantly decreased its ignition delay time. Compared with the aluminum powder with potassium fluoride addition of 5wt% (0.003 g), the ignition delay time of the aluminum powder decreased by 47.58 s than that of 15wt% (0.009 g). Pure aluminum powder cannot be ignited in water vapor at 1000℃, and the aluminum powder with potassium fluoride addition can be ignited. Because potassium fluoride reacted with water vapor to form KOH, which can react with Al2O3 to destroy the oxidation shell of aluminum powder, thereby accelerating the reaction between aluminum and water vapor, and promoting the ignition of aluminum powder. Moreover, the combustion efficiency of aluminum powder with addition of potassium fluoride increased considerably with the increase the potassium fluoride contents, and its highest combustion efficiency was 82.24%, which was 38.75% higher than that of the aluminum powder without potassium fluoride addition. The increase of potassium fluoride content can produce more KOH, which increased the damage effect on the oxide film and promoted the reaction of aluminum with water vapor, thereby improving the combustion efficiency of the aluminum powder.