Polyurethane(PU) with enhanced mechanical strength and breaking elongation was prepared by adding cellulose crystals(CNC) to polyurethane, which was obtained by the established two-step method. CNC can be dispersed well in PU matrix. The tensile test shows that both the mechanical stress and breaking elongation can be improved over 140% comparing with pure polyurethane matrix due to the formation of hydrogen bonds between PU and CNC, with the addition of 1% CNC. Besides, the PU/CNC material exhibits good self-healing properties because the restoration of dynamic hydrogen bonds among the materials. The breaking stress and elongation of PU/CNC-1% can reach 5.4 MPa and 1113% respectively after self-healing at 50 ℃ for 36 h.