Fumaronitrile is useful as intermediates in the production of pharmaceuticals, industrial chemicals and various other useful compounds and as a starting monomer for polymer synthesis. It is the optimal candidate to present excellent flame-retardant effect by forming a SN-like structure after polymerization. More importantly, with the reaction of unsaturated bond, free nitrile groups are anchored in the polymer chains and the spontaneous reaction with Li anode is therefore inhibited.