Abstract: Hydrotreated oil samples from guard catalyst zone, HDM，HDS and HDN zones were collected respectively from a fixed-bed hydrotreating device. The properties of asphaltenes from residue feedstock and the obtained samples were analyzed, as well as the average molecular weight of asphaltenes and the stability parameter of residue colloidal was calculated. Results showed that with the increase of hydrotreating severity, the C，H，S，N，Ni，V and Fe contents in the asphaltenes of treated oil samples decreased significantly, the average molecular weight of asphaltenes and the stability parameter of residue colloidal decreased as well.

Key words: asphaltenes, petroleumresidue, hydrogenation, character, study method