Abstract: When earthquake happens, the propagation of the seismic wave results in the displacement of the surface soil of the earth. As the surface soil moves towards the axial direction of the pipeline, the tensile stress in the pipeline is produced. The bending pipeline is composed of longitudinal pipe, transversal pipe and elbow. As the displacement of the surface soil occurs in the axial direction of longitudingal pipe, the transversal pipe is pused. This brings about bending movement in the elbow. At the end of this paper, under the condition of ignoring the inertia force, analysis of the stress for the pipeline and bending pipe are made respectively, and simplified calculation method for the strength of buried pipe is put forward in the field case.