Although the mechanism of coal tar hydrogenation technology has not been fully revealed, many enterprises have realized the industrialization of this technology through the reference of crude oil hydrogenation technology. Therefore, it will be very helpful for the development of this technology to present a research result close to industry. Based on four kinds of catalyst gradations, the hydrogenation experiments of different processes and a series of 1200 h long-term experiments were carried out in a four-tube fixed bed reactor with coal tar distillate (IBP approximate to 360 degrees C) as the raw material. First, based on the product composition of different reactor outlets, the composition changes and main reaction process of coal tar in four reactors were summarized. It was found that the reactions in the four reactions are different and related. The hydrogenation of olefins mainly takes place in the first reaction (230 degrees C, hydrofining guard catalyst and hydrodemetallization catalyst). Most of the oxygenated compounds were transformed in the second reactor (320 degrees C, hydrogenation catalyst I) but not completely. The hydrogenation of aromatics is mainly concentrated in the third and fourth reactors, but there are already signs of this reaction in the second reactor. Second, the influence of different process conditions on the product properties and the material balance under different process conditions were summarized. Finally, the stability of the grading system is verified by the long-term experiments.