Under different temperature and different stress conditions, the creep experiment of polyurethane foam was carried out, and the creep constitutive equation of polyurethane foam under high temperature was obtained by fitting the obtained creeptime curve with Modified Time Harding model. Comparing the steady state creep rate fitted by model with the steady state creep rate measured by experiment, it is found that the creep property of polyurethane polymer has an important relationship with temperature and stress level. As the temperature and the stress level increases, the creep behavior of the material is more pronounced. The creep curve at high temperature is divided into two phases. In the first phase, the creep rate is larger and the creep rate gradually decreases with time. In the second phase, the creep rate is small and remains basically constant. Modified Time Harding model can better predict the creep rate of polyurethane materials under high temperature conditions.