Gradation filling method of heavy oil hydrogenation treatment catalyst

A gradation filling method of a heavy oil hydrogenation treatment catalyst. A reaction system includes two or more hydrogenation reactors connected in series. From the second reactor, the activity and probable pore size of the catalyst are both gradually decreased according to the sequence of contact with a reaction material flow in the same reactor. Between two adjacent reactors, according to the sequence of contact with the reaction material flow, the activity of the catalyst at the bottom of one reactor is lower than that at the top of the next one reactor, and the probable pore size of the catalyst at the bottom of one reactor is not more than that at the top of the next one reactor. Meanwhile, the activity of the catalyst at the bottom of one reactor is lower than that at the bottom of the next one reactor, and the probable pore size of the catalyst at the bottom of one reactor is large than that at the top of the next one reactor.