Maleic anhydride was selectively hydrogenated into succinic anhydride over modified skeletal Ni under mild conditions. Effects of different solvents, initial concentration of maleic anhydride, reaction temperature and pressure have been investigated. Under the optimized reaction conditions of 0.2 MPa, 30 ℃ and using dioxane as solvent, the conversion of maleic anhydride and the selectivity of succinic anhydride are both close to 100% in 60 minutes. The reaction is a pseudo-zero order reaction, and the apparent activation energy of the catalytic hydrogenation of maleic is 27.1 kJ/mol.