Abstract: To investigate the influence of debondings on the bearing capacity of integral composite structures under pull-off load condition, the influence of debonding shape, debongding space, debonding location and debonding size on the tensile strength of composite L-joints was researched with a quantitative evaluation. An important characterization parameter about the influence of debonding was proposed. The results indicate that the tensile strength of L-joints shows little sensitive change for debonding shape and debonding space. But an obvious influence of debonding location and debonding size on the tensile strength of L-joints is found, especially debonding close to the stiffener core/skin interface has the most significantly influence on the tensile strength of L-joints. The tensile strength decreases with the debonding size increasing, especially with the debonding size in the stiffener core/skin interface increasing.