Nano Ru supported on carbon catalysts with different Ru nanoparticle sizes were reported for the aromatics (dioctyl phthalate, xylene, p-phenylenediamine, cinnamic acid and nitrobenzene) hydrogenation to the corresponding valueadded cyclohexane derivatives. Ru@C-DP prepared by facile deposition-precipitation strategy, exhibited the smaller Ru nanoparticle (NP) size 2.0 nm, higher Ru dispersion degree (60.2%) and larger Ru specific surface area (220.1 m 2 ⋅g Ru À 1 ) than Ru@C-EG and Ru@C-IM synthesized with ethylene glycol reduction and impregnation method, respectively. Ru@C-DP possessed excellent activity with aromatic conversion � 99% and cyclohexane derivative selectivity � 99%, which was attributed to its smaller Ru NP size, suggesting the presence of a size-dependent effect. Moreover, compared with the commercial Ru@C-ID catalyst, Ru@C-DP showed remarkable reusability in aromatic hydrogenation. After the several hydrogenation recycles, the catalyst lost some activity mainly account for the pore blocking by reactant/product molecules, part oxidation and aggregation of Ru NPs.