Abstract: Based on the deposit conditions of the oxygen functional groups in the low rank coal affected to the surface properties, the paper analyzed the content 0 f the oxygen functional groups in 11 kinds typical low rank coal at home and abroad and the percentage of the oxygen in total oxygen of the oxygen functional groups.It was found that the main oxygen functional groups in the low rank coal were hydroxyI and carboxyl.The percentage of the oxygen in the hydroxyI account for 34.79% ~ 5 3.00% of the total oxygen, the carboxyI content of China lignite was higher than the hydroxyl content and the hydroxyI content of the lignite in other countries was highe r than carboxyl content.Meanwhile, an analysis was conducted on the advantage and disadvantage of the two evaluation methods (chemical analysis method and the in strument analysis method) for the oxygen functional groups.The paper stressed the oxygen function groups affected to the low rank coal properties (water absorbency, Zeta level and contact angle) .The removal of the oxygen function groups could cause the surface properties of the low rank coal converted from water absorbency to h ydrophobicity and could reduce the water adsorption capacity of the low rank coal.All those would have important significances to the properties modified of the low ran k coal.