The prepolymer was synthesized using hydroxyl-terminated polybutadiene (HTPB), poly(butylene adipate) (PBA2000), isophorone diisocyanate (IPDI), 1,4-butanediol (BDO), ethylenediamine (EDA), and 2,2-dimethylolpropionic acid (DMPA) as the main raw materials. The prepolymer was then neutralized with triethylamine (TEA) to obtain HTPB-modified waterborne polyurethane. In the prepolymerization process, the molar ratio of isocyanate group (—NCO) and hydroxyl group (—OH) in the polyol was fixed 2.3∶1, the content of DMPA was 3.8%, and the waterborne polyurethane emulsion with a solid content of 38% (measured value) was finally prepared by adjusting the proportion of HTPB in the polyol. The effects of HTPB content in polyols on the particle size of emulsion, storage stability of emulsion, water resistance, mechanical properties, thermal stability were studied. The results show that with the gradual increase of the proportion of HTPB in polyols, the average particle size of waterborne polyurethane emulsion also increases, the stability gradually decreases, the glass transition temperature decreases first and then increases, and the lowest glass transition temperature can reach -46.84 ℃. The water absorption of the produced polyurethane films first increases and then decreases, while the water resistance first decreases and then increases, and the elongation at break and low-temperature flexibility both increase with the increase of the proportion of HTPB in the polyol.