The invention discloses a photocurable waterborne hyperbranched resin and a preparation method thereof. The waterborne hyperbranched resin is synthesized through reacting 1-6 wt% of a polyol, 10-50 wt% of a polyhydroxy acid, 6-25 wt% of a polybasic acid anhydride, 10-45 wt% of isocyanate, 4-6 wt% of a neutralizer and 10-30 wt% of acrylate; the polyhydroxy acid is one or more of dimethylolpropionicacid, dihydroxybutyric acid, ethylenediamine butyl sulfonic acid and glycollic acid; and the polybasic anhydride is one or more of phthalic anhydride, maleic anhydride, trimellitic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, butanedioic anhydride and adipic acid anhydride. The photocurable waterborne hyperbranched resin has a good storage stability; and a film formed bythe resin under the action of a photoinitiator has excellent water resistance, hardness, aging resistance, chemical resistance and pollution resistance, also has the characteristics of high glossiness, good wear resistance, strong adhesion, high fullness, excellent impact resistance and the like, and is widely applied to surface radiation coating and protection of products such as wood plastic andthe like.