Abstract: Dicyclopentadiene dioxide epoxy (DCPDE) resin was modified by polyurethane (PU) grafting interpenetrating polymer networks (IPNs) based on copolymer (CPMI-co-EMDCPE) as curing agent in order to increase the thermal stability and compatibility of PU/DCPDE IPNs，which was started from N-(p-carboxyphenyl) maleimide (CPMI) and ethylene glycol monodicyclopentenylether (EMDCPE) monomers. Infrared spectral analysis was used to characterize the chemical structures of the copolymer and the IPNs. The mechanical properties，thermal stability and morphology of the resulted coatings were also investigated. The results indicated that the formation of DCPDE/PU IPNs increased flexibility，traction and strike of resulted coatings according to their nature and percentage concentration. The incorporation of copolymers (CPMI-co-EMDCPE) as curing agent into the polyurethane modified dicyclopentadiene dioxide epoxy resin universally increased thermal stability of DCPDE/PU IPNs. Surface morphology of modified dicyclopentadiene dioxide epoxy resin investigated by scanning electron microscopy (SEM) showed that modified DCPDE resin exhibited heterogeneous morphology.