Abstract: The creep camber of a high-speed railway bridge should be carefully considered. In the case of satisfying the mechanical performance, a twice-prestressed composite beam has the advantages of reducing the creep camber and is worth popularizing. Due to different construction technology, the dead-load stresses and concrete ages of two periods are different. Creep deformations have restraints on each other, which causes a stress on the contact surface. This paper adopts an age-adjusted effective modulus instead of modulus of concrete, and uses trigonometric progression to describe the stress on the contact surface to get the stress by the minimum excess principle based on deformation compatibility. The distribution of the stress obtained from a material example, which can provide references for the shear resistance design of the contact surface.