In order to increase the toughness of epoxy resin and make full use of biological resources, a tung oil-based hyperbranched polymer (TOHBP) was synthesized. The structure of the TOHBP was determined by FTIR, NMR and gel permeation chromatography (GPC). After TOHBP was incorporated into an epoxy/polyetherdiamine curing system, different analytical studies were carried out to characterize samples of each formation. The results show simultaneous improvement in the impact strength (62.79 kJ m⁻²), tensile strength (73.01 MPa), modulus (3116 MPa) and glass transition temperature (T_g) (86.62 °C) compared with neat epoxy resin (20.07 kJ m⁻², 67.97 MPa, 2610 MPa and 81.48 °C, respectively). In addition, the significant improvement in impact strength and the simultaneous reinforcement of other properties suggest that TOHBP provides a better toughening and strengthening ability than many other reported oil-based hyperbranched polymers (HBPs) and petroleum-based polymers. The results indicate that this renewable material is a promising modifier, and may provide an alternative to replace petroleum-based materials that increase the toughness of epoxy resins.