In order to apply a smart damper using polyurethane rubber spring to power plant facilities, it is necessary to consider the environmental temperature at the location where the damper is installed. Therefore, in this study, we study the characteristic change of polyurethane rubber springs according to temperature by hardness measurement and behavior test at various temperature. For the temperature characteristics experiment, two types of cylinder shaped polyurethane rubber springs with different outer diameters were fabricated, and hardness measurement, precompessed and dynamic behavior tests were performed with temperature. As a result of the precompressed and the 5Hz dynamic behavior test at 115℃, rigid body load and load bandwidth were reduced by the plastic deformation. The using limit temperature of the polyurethane rubber spring analyzed by the experimental results is estimated to be below 85℃.