Abstract: Based on plane cross-section assumption,considering the nonlinear behavior of material,the load-deflection(P-f)relationship curve of concrete beam strengthened with prestressed carbon fiber sheet(CFS)are obtained by step increasing the compressive strain of the extreme concrete fiber gradually.The calculated P-f curves of 5 prestressed CFS strengthened concrete beams and 4 CFS strengthened concrete beams are in good agreement with the experimental results.Using the analytical model,a study of the beam considering secondary load is presented.And the influences of initial strain in CFS,depth of section of the CFS strengthened concrete beam and prestress force are investigated.The results indicate that the high strength will be mobilized effectively by prestressing carbon fiber sheet;while considering secondary load,the behavior of the beam repaired with prestressed CFS is superior to that with non-prestressed CFS;and the stress hysteresis can be avoided to a certain extent.