The conversion of abundant biomass and their derivatives into high value-added fuels and chemicals is envisaged as a promising green avenue to reduce our reliance on conventional fossil resources. Among them, the pyrolysis of lignocellulose has become a green and economic means for mass production of bio-oils to substitute fossil fuels. However, due to the rich oxygen contents, the obtained bio-oils possess relatively low energy density and could cause damage to engines. The catalytic hydrodeoxygenation (HDO) has therefore been employed to upgrade bio-oils with high energy density by selectively removing oxygen contents.