A plausible reaction pathway for maleic anhydride ( MA) hydrogenation is firstly proposed, which suggests that the CH4 is produced by the methanation of CO formed during the reaction rather than direct de-carbonization of tetrahydrofuran, and MA cannot be directly decyclized, subsequently de-carbonized to C-3 compounds and CO. This work sheds light on the superficial phenomenon for MA liquid hydrogenation reported by other researchers, and may better explain the reaction process both in liquid and vapor phase MA hydrogenation. These results are important to understand the mechanism and reaction pathway of MA hydrogenation, and to facilitate the decrease of production cost in industrial plant.