Abstract: Debonding failure is of concern in reinforced concrete (RC) structures strengthened with carbon fiber sheets (CFSs). Nine RC beams strengthened with CFSs were investigated and the debonding load and failure mode were examined. The limit stress status of debond failure is analyzed according to tested data. A criterion of debonding failure is put forward after stress analysis in bond area. A calculation method for debonding capacity of reinforced concrete beams strengthened with CFSs is established accordingly. The shear stress and normal stress in bond area are both involved in this method. At the same time, the transverse shear displacement of U-shape carbon fiber sheets is considered. The method is validated through comparing the computational results with the test values. The design methodology of reinforced concrete beams strengthened with Carbon Fiber Sheets is improved.