Highly cross-linked polyurethanes based on Diels-Alder (DA) reaction have high hardness but poor toughness. A modified polyurethane with three-furyl diol (TF) was synthesized innovatively to improve its mechanical properties. Three-furyl diol (TF) and hydroxyl terminated polyurethane IDI-TF were synthesized first. Then the reaction of IDI-TF with xylene bismaleimide (BMI) generates cross-linked polyurethane ITB-PU (its soft segment content is 11.5%). Finally, the properties of the polyurethane ITB-PU were characterized by a series of methods. It can be observed that the DA reaction occurred at 50.33 degrees C, the r-DA reaction at 69.55 degrees C. When heated at 80 degrees C for 6 h, the self-healing efficiency of the ITB-PU was 43.91% known from the tensile test, and cracks on it virtually disappeared seen from polarizing microscope (POM). When heat was preserved for 12 h, the self-healing efficiency can reach 80.02%.