The present invention relates to a hydrogenation method for flexible production of diesel oil and chemical raw material, heavy raw material and optional light raw material mix with hydrogen, and enter into a first hydrogenation reaction area and a second hydrogenation reaction area, and contact with hydrogenation treatment catalyst I and hydrogenation cracking catalyst respectively and perform reaction. Without separation, the reactant mixes with the light raw material and enters into a third hydrogenation reaction area, under the action of hydrogenation treatment catalyst II, the mixture performs the reaction, through the reactant is cooled, separated and fractionated, the light naphtha distillate, the heavy naphtha distillate, the diesel oil distillate and the tail oil distillate can be got. The method provided by the present invention combines the hydrogenation treatment and the hydrogenation cracking organically, the heavy distillates such as decompression gas oil, etc. and the ungraded light distillate got from the second time processing are used as raw material, the operation can be adjusted flexibly according to the market demand, so as to produce high quality diesel oil or chemical raw material in the maximum volume, wherein the diesel oil can meet the requirement of Europe IV fuel specification.