It is difficult to assess the mechanical properties and deformation of urban sewage tunnel in whole service life quantitatively and dynamically. The corrosion mechanism of concrete pipe for sewage discharge is studied. Calculation model of segment structural performance degradation under multifactor coupling action is established. The mechanical properties and deformation of Donghaoyong test section is analyzed by Matlab software. The numerical analysis results show that: 1) The internal force of sewage tunnel in whole service life continuously increases. The axial forces on both sides of the sewage tunnel are the largest and increase continuously. 2) The negative bending moment on the both sides of the sewage tunnel are the largest; the positive bending moment on the bottom of the sewage tunnel is the smallest; and they increase obviously in poststage service life. 3) The maximum positive shear forces occur at 135° and 315° positions; the maximum negative shear forces occur at 45° and 225° positions; and they increase obviously in poststage service life. 4) The drying and watering cycle zone is the worst zone for internal force variation of the sewage tunnel; the maximum vertical displacement occurs at crown top; and the maximum horizontal displacements occur at 18°and 162° positions.