The invention relates to a hydrogenation catalyst with gradient descending distribution of active metal and acidic assistant concentration and a preparation method thereof. The preparation method comprises the steps of: by preparing a more concentrated active metal solution and an acidic assitant solution, spraying and dipping a carrier until saturation with the method of adding deionized water or ammonia water step by step to dilute the solution in the dipping process of the carrier; or by preparing at least two active metal solution and acidic assistant solution which are different in concentration, orderly spraying and dipping the carrier according to the concentration of the active metal solution and the acidic assistant solution from high to low; or dipping with a solution containinghigher concentration of acidic assistant, adding a solution with lower concentration of the acidic assistant to dip and deionized water to dilute step by step in the dipping process; drying and roasting; dipping with solution with higher concentration of active metal, adding a solution with lower concentration of active metal to dip and deionized water to dilute step by step in the dipping process; or carrying out the step of acidic assistant dipping after the metal dipping; and drying and roasting. The hydrogenation catalyst has excellent properties of demetalization, carbon residue removal,desulfurization, denitrification activity and stability.