Abstract: In order to solve the bad fouling on heating surfaces caused by using coal from Shaerhu Coal Mine as the fuel of utility boilers, the sodium content was measured by the combination method of one-step-extraction and 600 °C low-temperature ashing, the sodium release proportion in coals were tested at different temper atures and national standards ashing with different additives, such as kaolin, Al2O3, SiO2, CaCO3, SiO2/Al2O3 ( mass rationof5 : 1) and percentages. The results sho wed that the content of Na2O was 0.907%, the sodium release proportion increased when the ashing temperature ascended, and the sodium release proportion would b e enhanced when taking CaCO3 as the additive, while kaolin played an obviously negative role, the sodium release proportion reduced not much when the additive con sisted of Al2O3 or SiO2/Al2O3, and Al2O3 was the primary effective factor, while SiO2 affected the sodium release proportion lttle.