The invention discloses a flexible hydro-upgrading process for inferior diesel oil. The diesel raw material enters a hydrofining reactor, and the material passing through the upper hydrofining catalyst bed layer is divided into two parts; one strand of material is pumped out of the refining reactor through the middle of the bed layer, and enters a supplementary hydrofining reactor for a supplementary hydrogenation reaction; and the other strand of material continues to flow downwards through a hydrofining catalyst bed layer at the lower part, the hydrofining material flow continues to enter ahydro-upgrading reactor, the obtained hydro-upgrading reaction material and the obtained supplementary hydrofining reaction material are subjected to gas-liquid separation and fractionation respectively, and a high-quality diesel product and a high-quality FCC feed are obtained. The invention firstly provides a hydrogenation combination process for simultaneously producing two or more diesel fractions with different meshes on one set of hydrogenation process device, so that the coupling operation of the hydrofining reactor and the supplementary hydrofining reactor can be realized by fully utilizing heat carried by a part of refined materials.