The present paper deals with an influence of the distortional-lateral buckling mode on the interactive buckling of thin-walled short channels with imperfections subjected to the bending moment when the shear lag phenomenon and distortional deformations are taken into account. A plate model (2D) is adopted for the channel section. The structure is assumed to be simply supported at the ends. A method of the modal solution to the coupled buckling problem within the Koiter's asymptotic theory, using the semi-analytical method (SAM) and the transition matrix method, was applied. The calculations and experimental preliminary tests were carried out for short channels.