The work aims to study the effects of the structure of hyperbranched polythioether on properties of epoxy acrylate composite UV-curable coatings. At first, trimethylolpropane tris (3-mercaptopropionate) (TMPMP) and glycidyl methacrylate (GMA) were used as raw materials to synthesize thiol-terminated hyperbranched polythioether (HBP-SH) by one-pot method, using the thiol-click chemistry reaction with significant difference in reaction rate. Further then, tetrahydrofurfuryl acrylate (THFA) was used as the modified monomer, and the molar ratio of thiol-terminated hyperbranched polythioether (HBP-SH) to tetrahydrofurfuryl acrylate (THFA) was 1∶1, 1∶0.9 and 1∶0.8, respectively. The hyperbranched polythioethers (HBP-xTHFA, x=100%, 90%, 80%) with end group modification ratios of 100%, 90%, and 80% were also synthesized by one-pot method. Finally, the prepared HBP-xTHFA were added to commercial epoxy acrylate (EA) to prepare hyperbranched polythioether modified epoxy acrylate composite UV curable coatings. The comprehensive performance of the composite UV curable coatings with HBP-xTHFA was higher than that of pure epoxy acrylate (EA) coatings. The adhesion and curing shrinkage rate test results indicated that as the modification ratio of hyperbranched polythioether end groups increases, the adhesion of coatings increased and the curing shrinkage rate decreased. When the end group modification ratio was 100% and the addition amount was 2wt%, the composite UV curable coating exhibited the best adhesion and the smallest curing shrinkage. The impact resistance and tensile test results showed that the brittleness of composite UV curable films added with HBP-xTHFA was improved. The composite UV curable films with HBP-xTHFA still maintained high double bond conversion by real-time infrared. The prepared hyperbranched polythioethers by one-pot method have simple synthesis steps. Adding it to commercial epoxy acrylate (EA) system can reduce the curing shrinkage rate of UV curable system, improve the adhesion of coatings and improve the brittleness of UV curable epoxy acrylate coatings. The hyperbranched polythioethers possess the prospects of industrial application.