An aza-Michael addition between 2,6-di-t-butyl-7-phenyl-p-quinone methide and secondary amine was demonstrated to show a dynamic covalent reaction property under ambient conditions requiring no external stimuli. Based on this dynamic covalent chemistry, a novel dynamic covalent cross-linked polyurethane material was developed to achieve wonderful self-healing ability under ambient conditions without external stimuli. In addition, this cross-linked polyurethane behaved with excellent catalyst-free recyclability and reprocessability at a mild temperature of 60 °C.