Hydrothermal liquefaction (HTL) bio-crude from microalgae cannot be directly used as transportation fuels due to poor quality. A new approach for its application is integration of it and modern petroleum processing industry. The chemical properties of HTL bio-crude

including chemical composition

functional groups and heteroatom compounds constitution are summarized in this paper. The characterization methods including GC-MS

FTIR

NMR

FT-ICR MS were compared and analyzed. Formation mechanism and upgrading of HTL bio-crude were also briefly reviewed. The focus is on higher oxygenated and nitrogenous compounds content in HTL bio-crude

higher aromaticity and unsaturation degree comparing with heavy crude oil or residue oil. Catalytic hydrotreating could effectively remove heteroatom and increase hydrocarbon content. The development of microalgae-based bio-fuels depends on not only the progress in upgrading technique but also the improvement of characterization methods.