Abstract: Taking advantage of FRP (fiber-reinforced polymer) that is anticorrosive, light and of high strength, the FRP strips were stuck on the flange bottom of H-beam of a simply-supported prestressed steel-concrete composite beam, thus enabling the composite beam to reduce effectively its deformation and improve its load-bearing capacity. Based on numerical integration and taking account of the beam' s nonlinear materials, the nonlinear analytic models are developed for the beam in the whole process from receiving load to failure. Then, the computation procedure is programmed to obtain the relationship between load and deformation and that between load and prestressed increment. The whole process is thus analyzed nonlinearly to clarify the working characteristics of the composite beam in different stress/strain variation phases. An example is given to verify the validity of the analytic models proposed.