Abstract: On the basis of the theory of thin-walled member, thecontinuity of warping in analysis of bending shearing flow and warpingshearing flow in thin-walled box-girder is studied. With the continuitycondition of warping, the formula of warping shearing flow in restrained torsion ofthin-walled box-girder is established. The error in relevent referencesis pointed out and corrected. The warping shearing flow in a cantileverbox girder under restrained torsion is calculated.