Fabrication of thermosets with high glass transition temperature (T-g) has been a challenge in recent years. In this study, a facile method is presented to prepare high T-g polymers with good thermostability. Firstly a chiral palladium (II) complex bearing an iminophenyl oxazolinylphenylamine (IPOPA) ligand, IPOPA-PdCl, has been prepared and characterized, which exhibits high activities for vinyl-(co)polymerization of norbornene (NB) and 5-vinyl-2-norbornene (VNB) in the presence of various cocatalysts. Then the synthesized copolymer P(NB-vinylNB) is epoxidized to generate epoxy product P(NB-epoxyNB). Phytic acid (PA), which is a naturally component in plants, is then used to cross-link P(NB-epoxyNB) for further restricting molecular motions. The obtained crosslinked P(NB-epoxyNB)-PA exhibits high T-g of up to 351.5 degrees C. This work not only provides insight into the design of novel semi-salen type palladium (II)-based catalyst for vinyl-(co)polymerization of NB and its derivative, but also shows a feasible strategy to design thermosetting PNB-based polymer with high T-g and thermostability.