Ruthenium catalysts with different supports were prepared by equal volume impregnation method. Ru/Al2O3 was selected as the best catalyst for the hydrogenation of diisoononyl phthalate to diisoonyl 1,2-cyclohexane dicarboxylate. The support Al2O3 was modified by hydrothermal treatment at 140 ℃ for 4h, pore forming agent addition of 1%, binder addition of 5%, calcination at 700 ℃ for 4h. Al2O3 with different ruthenium loading amount was characterized and evaluated. The results showed that the best ruthenium loading amount was 0.3%. The conversion of diisoonyl phthalate was 98.9% and the selectivity of diisoonyl 1,2-cyclohexanedicarboxylate was 97.1% under the conditions of temperature 150 ℃, pressure 5MPa and space velocity 0.25h-1.