Abstract: In order to study the moisture re-adsorption mechanism of lignite after drying, the oxygen-containing functional groups content in lignite after pyrolysis at low temperature and before and after hydrogen peroxide oxidation were tested by means of chemical titration method. The effects of the oxygen-containing functional gr oups content changes on lignite moisture re-adsorption characteristics were investigated in a constant humidity environment. The results showed that the lignite surface hydrophily decreased after low temperature pyrolysis deoxidation. As decreasing of oxygen-containing functional groups content, the moisture adsorption rates reduced. The oxygen-containing functional groups content of coal samples increased after hydrogen peroxide oxidation. The enhancement extent of oxygen-containing functional groups content were found to increase as the oxidation temperature raised, the moisture absorption rates also increased. The significant positive correlation existed bet ween the oxygen-containing functional groups content and moisture absorption.