An experimental study on the long-term performance of prestressed composite beams has been carried out for the first time in China. The long-term deformation of prestressed composite beams, the strain of prestressed tendons, the strain of steel beams, and the slip between steel beams and concrete slabs are systematically studied through a one-year long-term load test. Based on the method of effective modulus of age adjustment, the creep stiffness matrix and creep force vector of prestressed composite beam elements are derived, and a time-dependent analysis program is developed.