The invention relates to a preparation method of light/biological dual-degradation high-water-absorption resin based on natural polymer. According to the method, with cyclohexane as the solvent, a Span-series surface active agent as the dispersing agent, potassium persulfate as the initiator and N,N-methylenebis acrylamide as the crosslinking agent, by means of a reverse-phase suspension polymerization method, starch or carboxymethylcellulose or chitosan or other natural polymer reacts with acrylic acid and acrylamide monomer to prepare the light/biological dual-degradation high-water-absorption resin. According to the high-water-absorption resin, with natural polymer as the biological degradation source and nanometer TiO2 particles as the light degradation source, the nanometer TiO2 particles are evenly distributed in the high-water-absorption resin, the problem that ordinary high-water-absorption resin is difficult to degrade can be effectively solved, and the environment pollution problem is solved.