Abstract: The thermal-structure couple analysis of cylinder under high temperature gradient was carried out by ABAQUS finite element code based on the physical and mechanical properties of SA508-III steel to obtain the temperature and stress distribution along the thickness. Making use of the creep parameters varied with temperature, the creep process of cylinder was analyzed. The creep strain and stress distributions along the thickness were predicted. The results show that because of the high temperature gradient, the stress distributions along the thickness can be divided into three regions; the middle region trend to be elastic region and the others are plastic region. The creep strain increases quickly and reaches the steady state since the creep occurs. The stress is relaxed and redistributed. A certain mutation appears in the elastic region of the cylinder.