The invention discloses bio-based aldehyde-free adhesive. The adhesive contains the following raw materials in parts by weight: 500-800 parts of bio-oil, 300-500 parts of isocyanate, 200-300 parts ofplant polyol and 1-2 parts of catalytic promoter. The adhesive disclosed by the invention has the beneficial effects that a biomass pyrolysis product: the bio-oil, which is rich in hydroxyl groups andrigid aromatic benzene ring structures is used as the main raw material, so that excellent water-resistant bonding strength and thermal stability can be given to the adhesive; harmful substances suchas formaldehyde and the like are not added in the preparation process of the adhesive; the adhesive has appropriate viscosity and storage period; and a glued artificial board adopting the adhesive has no formaldehyde release and meets the requirements of national standard type I plywood.