Fuente: Wipo "precision agriculture" The invention belongs to the field of polyurethane materials, and particularly relates to a preparation method of a bio-based hydrophilic polyurethane water-swelling elastomer, which comprises the following steps: step 1, uniformly mixing isocyanate, bio-based polycaprolactone polyol, polylactic acid polyol, a catalyst, polyethylene glycol and water, and reacting at room temperature to obtain a reaction solution; and step 2, foaming and curing the reaction liquid to obtain the bio-based hydrophilic polyurethane water-swelling elastic material. The hydrophilic polyurethane expansion elastomer prepared by the preparation method disclosed by the invention has better hydrophilicity and stable water expansion performance, also has better mechanical properties and better application prospects; the bio-based hydrophilic polyurethane water-swellable elastomer prepared by the method disclosed by the invention is low in preparation cost, suitable for large-scale batch production and beneficial to application of the bio-based hydrophilic polyurethane water-swellable elastomer.