Abstract: The sources and compositions of steam cracking C9 cut in China and overseas were reviewed. Hydrotreating is the key technology for C9 cut upgrading. Centering on the hydrotreating utilization of C9 cuts, several new processes were summarized, including production of premium boiling aromatic solvent or gasoline blend, flash oil hydrogenation to solvent and conversion of hydrogenated C9 cuts by hydrodealkylation and transalkylation to BTX (benzene, toluene, xylene). The hydrogenation technologies, as well as catalysts used in hydrotreating, were analyzed and compared, and feedstock pretreatment, reaction process and catalyst design were discussed.