Devices and methods for preparing oxygen-containing liquid fuel by bio-oil catalytic conversion. A device includes a biomass fast thermal cracking system for preparing bio-oil, a bio-oil oil-water separating system for separating the bio-oil into oil phase bio-oil and water phase bio-oil that is output to an oil phase bio-oil chemical chain hydrogen production system, and a water phase bio-oil catalytic hydrogenation system. The hydrogen production system outputs produced hydrogen to the water phase bio-oil catalytic hydrogenation system to prepare a liquid fuel. A method includes the steps: thermally cracking the biomass to prepare bio-oil, separating the water phase and the oil phase, producing hydrogen from the oil phase bio-oil through a chemical chain method so as to provide a hydrogen source for the water phase bio-oil to carry out two-stage catalytic hydrogenation in a slurry bed, and separating and purifying the hydrogenated products to obtain an oxygen-containing liquid fuel.