decrease of water content. Firstly, water originated from esterification can be removed from the upgraded bio-oil by anhydrous magnesium sulfate. Secondly, bound water contained in bio-oil was converted into free water because of the decrease of hydrophilic compounds (such as organic acid, 1-hydroxy-2-propanone, etc.). The released water can also be removed by anhydrous magnesium sulfate. Moreover, the reduced water content results in a sharp increase for the high heating value. In a word, the properties of biooil were improved obviously after upgrading process, suggesting that the upgraded bio-oil is more suitable to be used as boiler fuel.