The hyperbranched polyester with terminal hydroxyl groups was modified with maleic anhydride, and the hyperbranched maleate containing a great number of unsaturated double bonds in segmers was synthesized. The changes of viscosity, thermal stability and Tg on hyperbranched maleates with different modified degrees were analyzed and characterized. The hyperbranched maleates were used as prepolymer in UV-curable coating, and the effects of modified degrees on the adhesive strength, impact strength, flexibility, hardness and the solvent resistances of UV-curable coating were studied. The experiments indicated that the hyperbranched maleate was a kind of macromolecular material with low viscosity, good thermal stability and easy adjustable Tg. When the modified degree was 80%,the performances of the UV-curable coating were best, which the UV-curable time could reached 3s,the adhesive strength of coating was grade 1, impact strength was 48kgf.cm, the flexibility was above 7cm, the hardness reached 5H and it had the good solvent resistances.