A biphasic solvent system for converting biomass to prepare 2,5-hexanedione and a one-pot process for catalytically converting biomass to prepare 2,5-hexanedione with said biphasic solvent system are provided. The process includes the steps of contacting and reacting a biomass raw material with a hydrogenation catalyst using hydrogen gas as a hydrogen source in a heterogeneous system formed from an organic solvent, an inorganic salt and water to obtain 2,5-hexanedione. The hydrogenation catalyst includes a hydrogenation active component and a support. The support is selected from one or more of hydrophobic active carbon and graphene. The process can achieve efficient conversion of biomass without the participation of acid catalysts, and have a very high selectivity for the product 2,5-hexanedione.