The invention discloses a volume-phase hydrogenation catalyst and a preparation method thereof. The catalyst is spherical particles, and pore diameter distribution has the following characters: an average pore diameter d1 from a center of the catalyst particle to x*R is 50-100 nm, wherein x is 0.1-0.9, an average pore diameter d2 from the x*R to the outer surface of the catalyst is 120-180 nm, andd2-d1=40-130 nm, wherein R is a particle semidiameter of the volume-phase hydrogenation catalyst. The volume-phase hydrogenation catalyst has the following characters: a specific surface area is 250-350 m<2>/g, a pore volume is 0.8-1.0 mlg-1, and an average pore diameter is 50-150 nm. Additive concentration is gradually increased from the particle center to the outer surface. The volume-phase hydrogenation catalyst is larger in pore volume and pore diameter, and the pore diameter of the outer surface is greater than the pore diameter of the interior. Surface-phase reactive metal density of the catalyst is larger, a utilization ratio of a hydrogenation reactive metal and a utilization ratio of the interior of the catalyst are higher, a catalyst deactivation rate is reduced, and service life of the catalyst is improved. The method is capable of realizing continuous production of the hydrogenation catalyst, improving production efficiency, and reducing production cost.