The invention relates to polyurethaneurea hydrogel and preparation methods therefor. The preparation methods comprise two preparation methods. The first preparation methods is as follows: diisocyanate and catalysts are added in a polyethylene glycol (PEG) organic solution for reaction, then diamine chain extender is added, and products are obtained in the organic solvent after precipitation, wherein, the molar ratio of PEG, diisocyanate and diamine is 1:2:1. The second preparation method is as follows: N,N'-dicarbonyl diimidazole is added in a PEG organic solution for reaction, then excess diamine chain extender is added, macromolecules with amidogens at two ends are obtained, finally, diisocyanate is added, and products are obtained in the organic solvent after precipitation, wherein, the molar ratio of PEG and diisocyanate is 1:2. The polyurethaneurea hydrogel has advantages of large elongation and high tensile strength, and has shape memory functions. The polyurethaneurea hydrogel has application prospects at aspects of biomedical hydrogel, tissue engineering, hydrogel support materials, biomedical devices with shape memory functions and the like.