The invention discloses a preparation method of a degradable sand-fixing agent, belonging to the field of sand-fixing agents. The present invention takes peat soil, glucose and water and puts them into a container, mixes them evenly, sprays and dries them, collects the dry matter, performs ball milling, sieves, and collects the sieved particles; acetone, 1,4-butanediol, L-propane Put lactide and dibutyltin dilaurate into the reactor, use carbon dioxide protection, heat up the reaction, cool to room temperature, collect the reaction mixture, and recover acetone, collect the residue; the residue, toluene, trimethylolpropane three Put methacrylate, toluene diisocyanate, sieved particles and catalyst into the reaction kettle and stir, then add triethanolamine to raise the temperature and continue to stir, cool to room temperature, discharge, and collect the discharge; filter the discharge to recover the catalyst, and then Carry out rotary evaporation to recover toluene, collect the rotation residue, and mix the rotation residue, cactus glue and biological particles evenly to obtain a degradable sand-fixing agent.