There is an urgency to produce novel high-performance resins to support the rapid development of the aerospace field and the electronic industry. In the present work, we designed and consequently synthesized a benzoxazine monomer (oHPNI-fa) bearing both norbornene and furan groups through the flexible benzoxazine structural design capability. The molecular structure ofoHPNI-fawas verified by the combination characterization of nuclear magnetic resonance spectrum, FT-IR technology, and high-resolution mass spectrum. The thermally activated terpolymerization was monitored by in situ FT-IR as well as differential scanning calorimetry (DSC). Moreover, the low-temperature-curing characteristics ofoHPNI-fahave also been revealed and discussed in the current study. Furthermore, the curing kinetics of theoHPNI-fawere investigated by the Kissinger and Ozawa methods. The resulting highly cross-linked thermoset based onoHPNI-fashowed excellent thermal stability as well as flame retardancy (Td10of 425 °C, THR of 4.9 KJg−1). The strategy for molecular design utilized in the current work gives a guide to the development of high-performance resins which can potentially be applied in the aerospace and electronics industries.