The basic characteristics of the stress-strain-temperature relationship were investigated experimentally as part of the research on the mechanical properties of shape memory polymer of polyurethane series. The main results are summarized as follows.(1) The deformation resistance of the material increase with the number of cycles under cyclic deformation at temperatures above the glass transition temperature. (2)If training is performed before the practical use and the maximum strain is less than 1OO %, the constant recovery strain may be obtained under thermomechanical cycling.(3) The strain obtained at low temperature following the predeformation given at high temperature does not vary under thermomechanical cycling, which shows stable shape fixity of the material for cyclic deformation.