Abstract: The coke deposition of various aromatics on hydrocracking catalyst has been obtained using accelerated aging experiment. Acid strength distribution, pore structure and coke type of catalyst were measured by FT-IR,physical absorpmeter and thermal analysis. The results showed that for single ring aromatics, involving benzene, toluene, para-xylene, ethylbenzene and styrene, the characters of substituted-groups, including carbon chain length, number and saturation, could affect the amount of coke and pore character. Longer carbon chain, larger number and less saturation could result in more coke deposition on catalyst. For different rings aromatics without any substituted-group, involving benzene, naphthalene and phenanthrene, the amount of both general coke and the pseudo-graphite structure coke increase with the increase of aromatic rings, but the total amount of acid decreases gradually, especially for strong acid. For all aromatics, the specific surface area of deactivated catalyst decreases with the increase of the coke. The coke impenetrates in all pores and mainly deposited in small pore of catalyst, while some of coke could form mechanical pore on catalyst surface.