Abstract The strain dependence of the critical current, I c, of Bi2223/Ag/Ag-alloy composite superconducting tapes has been studied both experimentally and analytically under bending deformation. The microscopic observation after bending deformation indicated that delamination existed inside Bi2223 filaments and filament/matrix interface. Then, the former bending deformation analysis was modified to fit the existence of the delamination. The calculated critical current, I c, was almost the same as the experimental results when the delamination is fully located at the mid plane of the tape though the actual situation was partial in the width direction. Then the location of the delamination was moved in the thickness direction in the analysis. The calculated I c agreed well with the experimental results when the delamination location was moved to the compressive side.