Abstract: Creep damage analysis of hot outlet manifold of steam reformer under the ideal operating condition was carried out by finite element methods based on improved Liu-Murakami constitutive model. The results show that the improved Liu-Murakami model could predict the uniaxial creep curve of the manifold under different stress levels accurately. Under ideal conditions, the maximum Mises stress and the maximum principal stress in initial service stage appeared at the junction of the pigtail pipe and the manifold. During the service process, stress redistribution occurred in the manifold, the maximum Mises stress and the maximum principal stress were significantly reduced. After serving for 10⁵ h, the maximum damage value of the manifold was only 0.071.